Add support for sha256 repositories (#23894)

Currently only SHA1 repositories are supported by Gitea. This adds
support for alternate SHA256 with the additional aim of easier support
for additional hash types in the future.

Fixes: #13794
Limited by: https://github.com/go-git/go-git/issues/899
Depend on: #28138

<img width="776" alt="图片" src="5448c9a7-608e-4341-a149-5dd0069c9447">

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: 6543 <6543@obermui.de>

modules/structs/repo.go

@@ -105,6 +105,9 @@ type Repository struct {
 	AvatarURL                     string           `json:"avatar_url"`
 	Internal                      bool             `json:"internal"`
 	MirrorInterval                string           `json:"mirror_interval"`
+	// ObjectFormatName of the underlying git repository
+	// enum: sha1,sha256
+	ObjectFormatName string `json:"object_format_name"`
 	// swagger:strfmt date-time
 	MirrorUpdated time.Time     `json:"mirror_updated,omitempty"`
 	RepoTransfer  *RepoTransfer `json:"repo_transfer"`
@@ -139,6 +142,9 @@ type CreateRepoOption struct {
 	// TrustModel of the repository
 	// enum: default,collaborator,committer,collaboratorcommitter
 	TrustModel string `json:"trust_model"`
+	// ObjectFormatName of the underlying git repository
+	// enum: sha1,sha256
+	ObjectFormatName string `json:"object_format_name" binding:"MaxSize(6)"`
 }
 
 // EditRepoOption options when editing a repository's properties