feat(admin-controller): add route to fetch all circles

[cristianscheid]

• Resolves: #

Summary

The existing admin endpoint for fetching circles requires an emulated user:

• GET ocs/v2.php/apps/circles/admin/{emulated}/circles

Results are scoped to the emulated user, so only circles related to that specific user are returned.

This PR introduces a new admin endpoint that returns all circles from the instance without user scoping:

• GET ocs/v2.php/apps/circles/admin/circlesall

"/circlesall" was used instead of "/circlesAll" or "/circles-all" to follow the standard from another multiword endpoint already present: "/probecircles"

The authenticated admin user is used for auth only, not to scope results:

// lib/Controller/AdminController::circlesAll()

// no need for emulated user since results are not scoped to any specific user
$this->setLocalFederatedUser($this->userSession->getUser()->getUID());

Params available:

- limit
- offset
- filterPersonal
- filterSingle
- filterSystem
- filterHidden
- filterBackend

The filter params are related to those configs (defined on lib/Model/Circle):

- CFG_PERSONAL - personal circle, only the owner can see it
- CFG_SINGLE - circle with only one single member
- CFG_SYSTEM - system Circle (not managed by the official front-end)
- CFG_HIDDEN - hidden from listing, but available as a share entity
- CFG_BACKEND - fully hidden, only backend Circles

All filter params default to true (1). So to include, for example, personal circles in the results, you must explicitly pass ?filterPersonal=0 to disable the filter.

Below are some request examples:

# get circles using default params
curl -X GET \
  -u "admin:admin" \
  -H "OCS-APIRequest: true" \
  "http://nextcloud.local/ocs/v2.php/apps/circles/admin/circlesall"

# include personal circles
curl -X GET \
  -u "admin:admin" \
  -H "OCS-APIRequest: true" \
  "http://nextcloud.local/ocs/v2.php/apps/circles/admin/circlesall?filterPersonal=0"

# limit results to 50 and set offset of 25
curl -X GET \
  -u "admin:admin" \
  -H "OCS-APIRequest: true" \
  "http://nextcloud.local/ocs/v2.php/apps/circles/admin/circlesall?limit=50&offset=25" 

# include system and hidden circles
curl -X GET \
  -u "admin:admin" \
  -H "OCS-APIRequest: true" \
  "http://nextcloud.local/ocs/v2.php/apps/circles/admin/circlesall?filterSystem=0&filterHidden=0"

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