Re-gate collaboration + notifications behind the APW/WCP capability before release

[SvenAlHamad]

The comments (api-collaboration / app-collaboration) and notifications
(api-notifications / app-notifications) features are currently ungated
for development convenience — the Wcp.CanUseWorkflows capability check was
removed so they run without a workflows license.

Before release, re-wrap both so they only activate for licensed tenants:

• API: the feature registration in packages/api-collaboration/src/index.ts
  (and the notifications equivalent) — restore the capability guard around
  createCollaboration() / createNotifications().
• Admin: the app mount in packages/app-collaboration/src/app.tsx — re-wrap in
  the appropriate capability gate.

Search the codebase for TODO(before release) to find every spot that needs
re-gating.

Blocks release of the collaboration/notifications feature.