…ess (#62771)

This PR exposes the data layer implemented in https://github.com/sourcegraph/sourcegraph/pull/62706 via the Enterprise Portal API. We register the services proposed in #62263 and also set up tooling like gRPC UI locally for DX.

Auth is via SAMS M2M; sourcegraph/sourcegraph-accounts-sdk-go#28 and sourcegraph/sourcegraph-accounts#227 rolls out the new scopes, and sourcegraph/managed-services#1474 adds credentials for the enterprise-portal-dev deployment.

Closes CORE-112

## Test plan

https://github.com/sourcegraph/sourcegraph/pull/62706 has extensive testing of the data layer, and this PR expands on it a little bit. I tested the RPC layer by hand:

Create SAMS client for Enterprise Portal Dev in **accounts.sgdev.org**:

```sh
curl -s -X POST \
        -H "Authorization: Bearer $MANAGEMENT_SECRET" \
        https://accounts.sgdev.org/api/management/v1/identity-provider/clients \
--data '{"name": "enterprise-portal-dev", "scopes": [], "redirect_uris": ["https://enterprise-portal.sgdev.org"]}' | jq
```

Configure `sg.config.overwrite.yaml`

```yaml
  enterprise-portal:
    env:
      SRC_LOG_LEVEL: debug
      # sams-dev
      SAMS_URL: https://accounts.sgdev.org
      ENTERPRISE_PORTAL_SAMS_CLIENT_ID: "sams_cid_..."
      ENTERPRISE_PORTAL_SAMS_CLIENT_SECRET: "sams_cs_..."
```

Create a test client (later, we will do the same thing for Cody Gateway), also in **accounts.sgdev.org**:

```sh
curl -s -X POST \
        -H "Authorization: Bearer $MANAGEMENT_SECRET" \
        https://accounts.sgdev.org/api/management/v1/identity-provider/clients \
--data '{"name": "enterprise-portal-dev-reader", "scopes": ["enterprise_portal::codyaccess::read", "enterprise_portal::subscription::read"], "redirect_uris": ["https://enterprise-portal.sgdev.org"]}' | jq
```

Then:

```
sg run enterprise-portal
```

Navigate to the locally-enabled gRPC debug UI at http://localhost:6081/debug/grcpui, using https://github.com/sourcegraph/sourcegraph/pull/62883 to get an access token from our test client to add in the request metadata:

```sh
sg sams create-client-token -s 'enterprise_portal::codyaccess::read'
```

I'm using some local subscriptions I've made previously in `sg start dotcom`:

![image](https://github.com/sourcegraph/sourcegraph/assets/23356519/a55c6f0d-b0ae-4e68-8e4c-ccb6e2cc442d)

![image](https://github.com/sourcegraph/sourcegraph/assets/23356519/19d18104-1051-4a82-abe0-58010dd13a27)

Without a valid authorization header:

![image](https://github.com/sourcegraph/sourcegraph/assets/23356519/c9cf4c89-9902-48f8-ac41-daf9a63ca789)

Verified a lookup using the returned access tokens also works

---------

Co-authored-by: Jean-Hadrien Chabran <jh@chabran.fr>
Co-authored-by: Joe Chen <joe@sourcegraph.com>

…ses (#62932)

This PR implements the DB and RPC layer for the `subscriptions.ListEnterpriseSubscriptionLicenses` RPC proposed in https://github.com/sourcegraph/sourcegraph/pull/62263. Previous PRs https://github.com/sourcegraph/sourcegraph/pull/62706 and https://github.com/sourcegraph/sourcegraph/pull/62771 set up the scaffolding for implementing DB and RPC layers for Enterprise Portal, so now we can implement both in a single PR without massive diffs.

We need this RPC, in particular the `pageSize=1 archived=false` variant, for Cody Gateway to adopt Enterprise Portal, as Cody Gateway depends on license tags for certain features.

Closes https://linear.app/sourcegraph/issue/CORE-111

### Usage in Cody Gateway

In production (not internal-only mode), this should only be used for diagnostics information. In the future, we will revisit the current use cases (identifying if a subscription is dev/internal, and finding a subscription's display name) and replace this usage in Cody Gateway with one of:

 - subscriptionsv1.GetEnterpriseSubscription
 - expanded codyaccessv1.GetCodyAccess
 - more specialized codyaccessv2 that can get everything in one go

For now, needing another round-trip should be acceptable, and in the migration I'll make sure failure to fetch the active license is handled gracefully and won't affect customer usage.

For a more in-depth view, see https://github.com/sourcegraph/sourcegraph/pull/62934 for the implementation of the actual integration.

### DB query

Product `EXPLAIN ANALYZE` for a query for `archived=false subscriptionid='$S2-subscription-id'` shows this should be pretty quick:

```
                                                                                    QUERY PLAN                                                                                     
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=630.51..630.52 rows=2 width=1176) (actual time=1.311..1.313 rows=7 loops=1)
   Sort Key: licenses.created_at DESC
   Sort Method: quicksort  Memory: 39kB
   ->  Nested Loop Left Join  (cost=0.28..630.50 rows=2 width=1176) (actual time=0.300..1.292 rows=7 loops=1)
         Join Filter: (subscriptions.id = licenses.product_subscription_id)
         Filter: (subscriptions.archived_at IS NULL)
         ->  Seq Scan on product_licenses licenses  (cost=0.00..627.98 rows=2 width=1176) (actual time=0.277..1.263 rows=7 loops=1)
               Filter: (product_subscription_id = '58b95c21-c2d0-4b4b-8b15-bf1b926d3557'::uuid)
               Rows Removed by Filter: 3805
         ->  Materialize  (cost=0.28..2.50 rows=1 width=24) (actual time=0.003..0.003 rows=1 loops=7)
               ->  Index Scan using product_subscriptions_pkey on product_subscriptions subscriptions  (cost=0.28..2.50 rows=1 width=24) (actual time=0.019..0.019 rows=1 loops=1)
                     Index Cond: (id = '58b95c21-c2d0-4b4b-8b15-bf1b926d3557'::uuid)
 Planning Time: 0.113 ms
 Execution Time: 1.341 ms
(14 rows)
```

## Test plan

DB integration tests, and similar manual testing to https://github.com/sourcegraph/sourcegraph/pull/62771 for the RPC layer, but this time requesting the `subscription` scope when creating an access token:

```sh
sg sams create-client-token -s 'enterprise_portal::subscription::read'
```

![image](https://github.com/sourcegraph/sourcegraph/assets/23356519/0af7d6fb-4c01-4ddc-91f7-39640748d071)

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