Add option to prohibit fork if user reached maximum limit of repositories (#21848)

If user has reached the maximum limit of repositories:

- Before
  - disallow create
  - allow fork without limit
- This patch:
  - disallow create
  - disallow fork
- Add option `ALLOW_FORK_WITHOUT_MAXIMUM_LIMIT` (Default **true**) :
enable this allow user fork repositories without maximum number limit

fixed https://github.com/go-gitea/gitea/issues/21847

Signed-off-by: Xinyu Zhou <i@sourcehut.net>

modules/setting/repository.go

@@ -48,6 +48,7 @@ var (
 		AllowAdoptionOfUnadoptedRepositories    bool
 		AllowDeleteOfUnadoptedRepositories      bool
 		DisableDownloadSourceArchives           bool
+		AllowForkWithoutMaximumLimit            bool
 
 		// Repository editor settings
 		Editor struct {
@@ -160,6 +161,7 @@ var (
 		DisableMigrations:                       false,
 		DisableStars:                            false,
 		DefaultBranch:                           "main",
+		AllowForkWithoutMaximumLimit:            true,
 
 		// Repository editor settings
 		Editor: struct {