55325: ui: Transactions link between Sessions and Statements r=dhartunian a=elkmaster

Resolves: #55131, #56244

Release note (admin ui change): Link to the Transactions page is now shown
between the Sessions and Statements links in the left hand navigation. This more
clearly reflects the hierarchy between the 3 concepts.

56346: testcluster: minor logging improvements r=andreimatei a=andreimatei

Log when TestCluster quiescing starts, and add a node log tag to each
node's quiescing ctx so messages from different nodes can be
disambiguated.

Release note: None

56437: cli, ui: dismiss release notes signup banner per environment variable r=knz,dhartunian a=nkodali

Previously, the signup banner could only be dismissed manually.
For internal testing purposes, this banner is unnecessary. This
change provides a way to dismiss the signup banner upon start of
a cluster via the cli by setting the environment variable
COCKROACH_UI_RELEASE_NOTES_SIGNUP_DISMISSED=true.

Resolves #46998

Release note: none

56533: backupccl: add feature flag support for BACKUP, RESTORE r=otan a=angelapwen

Follow-up to the RFC at #55778. This addresses the SRE use case mentioned in #51643 — instead of moving forward with a global denylist as the RFC indicated, we are prototyping feature flags via cluster settings to turn on/off requested features. The first part of the prototype will be done on `BACKUP` and `RESTORE` commands.

See [this doc](https://docs.google.com/document/d/1nZSdcK7YprL0P4TAuseY-mvlYnd82IaJ_ptAQDoWB6o/edit?) for further details. 

Note that the logic test under `ccl/backupccl/testdata/backup-restore/feature-flags` can be tested with the command `make test PKG=./pkg/ccl/backupccl TESTS='TestBackupRestoreDataDriven'`

— Commit message below — 

Adds a cluster setting to toggle a feature flag for the BACKUP and
RESTORE commands off and on; as well as a broad category for
Bulk IO commands. Currently disabling the cluster setting for Bulk
IO will only disable BACKUP and RESTORE jobs, but other types may
be included in this category in the future..

The feature is being introduced to address a Cockroach Cloud SRE
use case: needing  to disable certain categories of features in
case of cluster failure.

Release note (enterprise change): Adds cluster settings to enable/
disable the BACKUP and RESTORE commands. If a user attempts to use
these features while they are disabled, an error indicating that
the database administrator has disabled the feature is surfaced.

Example usage for the database administrator:
SET CLUSTER SETTING feature.bulkio.backup.enabled = FALSE;
SET CLUSTER SETTING feature.bulkio.backup.enabled = TRUE;
SET CLUSTER SETTING feature.bulkio.restore.enabled = FALSE;
SET CLUSTER SETTING feature.bulkio.restore.enabled = TRUE;
SET CLUSTER SETTING feature.bulkio.enabled = FALSE;
SET CLUSTER SETTING feature.bulkio.enabled = TRUE;

56591: ui: fix Overview screen in OSS builds r=dhartunian a=davepacheco

Previously, when using OSS builds (created with `make buildoss`), when
you loading the DB Console in your browser, you'd get "Page Not Found".
The route for the overview page was missing the leading '/'.  This bug
appears to have been introduced in
722c932.

Release note (admin ui change): This fixes a bug where users of
the OSS builds of CockroachDB would see "Page Not Found" when loading
the Console.

56600: roachpb: remove SetInner in favor of MustSetInner r=nvanbenschoten a=tbg

As of a recent commit, `ErrorDetail.SetInner` became unused, and
we can switch to a `MustSetInner` pattern for `ErrorDetail`. Since
the codegen involved is shared with {Request,Response}Union, those
lose the `SetInner` setter as well; we were always asserting on
the returned bool there anyway so this isn't changing anything.

Release note: None



Co-authored-by: Vlad Los <carrott9@gmail.com>
Co-authored-by: Andrei Matei <andrei@cockroachlabs.com>
Co-authored-by: Namrata Kodali <namrata@cockroachlabs.com>
Co-authored-by: angelapwen <angelaw@cockroachlabs.com>
Co-authored-by: Joshua M. Clulow <josh@sysmgr.org>
Co-authored-by: Tobias Grieger <tobias.b.grieger@gmail.com>