feat(teams): add ITeamFileResourceProvider for cross-provider file lookups

[pringelmann]

• Resolves: Team folders do not show up as part of team resources #61385

Summary

GET /teams/resources/{providerId}/{resourceId} asks a single provider which teams a resource belongs to. For files that provider is circles, which answers from oc_share. Anything that reaches a user by mount instead of by share is invisible, so a team folder never resolves to its team.

New optional OCP\Teams\ITeamFileResourceProvider. When the addressed provider implements it, TeamManager also asks every other provider that implements it, and merges the result.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI (tests)