refactor(datastore): move mapMediaType into MediaTypeReader

See merge request gitlab-org/container-registry!1633

Merged-by: João Pereira <jpereira@gitlab.com>
Approved-by: Jaime Martinez <jmartinez@gitlab.com>
Approved-by: João Pereira <jpereira@gitlab.com>
Co-authored-by: Hayley Swimelar <hswimelar@gitlab.com>

chore: add feature flag for dynamic media types

See merge request !1634

Merged-by: Suleimi Ahmed <sahmed@gitlab.com>
Approved-by: Jaime Martinez <jmartinez@gitlab.com>
Approved-by: Suleimi Ahmed <sahmed@gitlab.com>
Co-authored-by: Hayley Swimelar <hswimelar@gitlab.com>

fix(datastore): add constraint to prevent inserts of empty media types

See merge request gitlab-org/container-registry!1641

Merged-by: Suleimi Ahmed <sahmed@gitlab.com>
Approved-by: Simon Tomlinson <stomlinson@gitlab.com>
Approved-by: Jaime Martinez <jmartinez@gitlab.com>
Approved-by: Suleimi Ahmed <sahmed@gitlab.com>
Co-authored-by: Hayley Swimelar <hswimelar@gitlab.com>

feat(api/gitlab/v1): prevent early invalidation of top-level namespace cached sizes

See merge request gitlab-org/container-registry!1637

Merged-by: Hayley Swimelar <hswimelar@gitlab.com>
Approved-by: Suleimi Ahmed <sahmed@gitlab.com>
Approved-by: Hayley Swimelar <hswimelar@gitlab.com>
Co-authored-by: João Pereira <jpereira@gitlab.com>

## [4.3.0](gitlab-org/container-registry@v4.2.0-gitlab...v4.3.0-gitlab) (2024-06-04)

### ✨ Features ✨

* **api/gitlab/v1:** prevent early invalidation of top-level namespace cached sizes ([1fc2d081](gitlab-org/container-registry@1fc2d081))

### 🐛 Bug Fixes 🐛

* **datastore:** add constraint to prevent inserts of empty media types ([b4ee29bd](gitlab-org/container-registry@b4ee29bd))