To support Gateway API-style routes in the outbound proxy, we need to begin
discovering this route configuration from the control plane (via the new
`OutboundPolicies` API).

This change updates the proxy as follows:

1. Policy controller configuration is now required for the proxy.
   Previously, the policy API was optionally configured for the inbound
   proxy.
2. The sidecar and ingress proxies are updated to use client policies.
   Service profile configurations continue to be used when they include
   HTTP routes and/or traffic split. Otherwise, a client policy is used
   to route traffic.

Outbound policies are currently discovered for *all* outbound IP addresses. Over
time, the policy controller will assume responsibility to make *all* routing
decisions.  It does not yet serve responses for all cases, however, so some
fallback behavior exists to use endpoint metadata from profile discovery,
if it exists.

The multi-cluster gateway configuration does not yet use policies for
outbound routing. Furthermore, the proxy reports an IP logical address for
policy routes (instead of a named address, as is done with profiles). There
are no new metrics or labels introduced in this PR. Metrics changes will be made
in follow-up changes.

---

* outbound: Decouple backend caching from request distribution (linkerd/linkerd2-proxy#2284)
* build(deps): bump socket2 from 0.4.7 to 0.4.9 (linkerd/linkerd2-proxy#2290)
* README: comment just-cargo and make it more clear (linkerd/linkerd2-proxy#2292)
* build(deps): bump prettyplease from 0.1.23 to 0.1.24 (linkerd/linkerd2-proxy#2293)
* build(deps): bump tokio from 1.25.0 to 1.26.0 (linkerd/linkerd2-proxy#2286)
* build(deps): bump petgraph from 0.6.2 to 0.6.3 (linkerd/linkerd2-proxy#2285)
* client-policy: add protobuf conversion (linkerd/linkerd2-proxy#2289)
* integration: add test policy controller (linkerd/linkerd2-proxy#2288)
* outbound: change `push_discover` to take a `Service` (linkerd/linkerd2-proxy#2291)
* build(deps): bump rustix from 0.36.7 to 0.36.9 (linkerd/linkerd2-proxy#2295)
* build(deps): bump serde_json from 1.0.93 to 1.0.94 (linkerd/linkerd2-proxy#2296)
* build(deps): bump async-trait from 0.1.64 to 0.1.66 (linkerd/linkerd2-proxy#2297)
* build(deps): bump thiserror from 1.0.38 to 1.0.39 (linkerd/linkerd2-proxy#2298)
* build(deps): bump mio from 0.8.5 to 0.8.6 (linkerd/linkerd2-proxy#2299)
* separate policy client config from `inbound::Config` (linkerd/linkerd2-proxy#2307)
* outbound: Require ClientPolicy discovery (linkerd/linkerd2-proxy#2265)

Signed-off-by: Oliver Gould <ver@buoyant.io>

To support Gateway API-style routes in the outbound proxy, we need to begin
discovering this route configuration from the control plane (via the new
`OutboundPolicies` API).

This change updates the proxy as follows:

1. Policy controller configuration is now required for the proxy.
   Previously, the policy API was optionally configured for the inbound
   proxy.
2. The sidecar and ingress proxies are updated to use client policies.
   Service profile configurations continue to be used when they include
   HTTP routes and/or traffic split. Otherwise, a client policy is used
   to route traffic.

Outbound policies are currently discovered for *all* outbound IP addresses. Over
time, the policy controller will assume responsibility to make *all* routing
decisions.  It does not yet serve responses for all cases, however, so some
fallback behavior exists to use endpoint metadata from profile discovery,
if it exists.

The multi-cluster gateway configuration does not yet use policies for
outbound routing. Furthermore, the proxy reports an IP logical address for
policy routes (instead of a named address, as is done with profiles). There
are no new metrics or labels introduced in this PR. Metrics changes will be made
in follow-up changes.

---

* outbound: Decouple backend caching from request distribution (linkerd/linkerd2-proxy#2284)
* build(deps): bump socket2 from 0.4.7 to 0.4.9 (linkerd/linkerd2-proxy#2290)
* README: comment just-cargo and make it more clear (linkerd/linkerd2-proxy#2292)
* build(deps): bump prettyplease from 0.1.23 to 0.1.24 (linkerd/linkerd2-proxy#2293)
* build(deps): bump tokio from 1.25.0 to 1.26.0 (linkerd/linkerd2-proxy#2286)
* build(deps): bump petgraph from 0.6.2 to 0.6.3 (linkerd/linkerd2-proxy#2285)
* client-policy: add protobuf conversion (linkerd/linkerd2-proxy#2289)
* integration: add test policy controller (linkerd/linkerd2-proxy#2288)
* outbound: change `push_discover` to take a `Service` (linkerd/linkerd2-proxy#2291)
* build(deps): bump rustix from 0.36.7 to 0.36.9 (linkerd/linkerd2-proxy#2295)
* build(deps): bump serde_json from 1.0.93 to 1.0.94 (linkerd/linkerd2-proxy#2296)
* build(deps): bump async-trait from 0.1.64 to 0.1.66 (linkerd/linkerd2-proxy#2297)
* build(deps): bump thiserror from 1.0.38 to 1.0.39 (linkerd/linkerd2-proxy#2298)
* build(deps): bump mio from 0.8.5 to 0.8.6 (linkerd/linkerd2-proxy#2299)
* separate policy client config from `inbound::Config` (linkerd/linkerd2-proxy#2307)
* outbound: Require ClientPolicy discovery (linkerd/linkerd2-proxy#2265)
* just: Fix docker tag formatting (linkerd/linkerd2-proxy#2312)
* outbound: Report concrete authorities for policies (linkerd/linkerd2-proxy#2313)

Signed-off-by: Oliver Gould <ver@buoyant.io>