feat(xo-server/resourceSet): add 'usage' property resourceSet

[MathieuRA]

Description

See zammad#20996 Show used resources even when they are unlimited

Checklist

• Commit
  • Title follows commit conventions
  • Reference the relevant issue (Fixes #007, See xoa-support#42, See https://...)
  • If bug fix, add Introduced by
• Changelog
  • If visible by XOA users, add changelog entry
  • Update "Packages to release" in CHANGELOG.unreleased.md
• PR
  • If UI changes, add screenshots
  • If not finished or not tested, open as Draft

[MathieuRA]

Good for me.