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="https://github.com/go-gitea/gitea/assets/81045/5448c9a7-608e-4341-a149-5dd0069c9447">

---------

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

models/issues/comment.go

@@ -270,7 +270,7 @@ type Comment struct {
 	UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
 
 	// Reference issue in commit message
-	CommitSHA string `xorm:"VARCHAR(40)"`
+	CommitSHA string `xorm:"VARCHAR(64)"`
 
 	Attachments []*repo_model.Attachment `xorm:"-"`
 	Reactions   ReactionList             `xorm:"-"`

models/issues/pull.go

@@ -171,11 +171,11 @@ type PullRequest struct {
 	HeadBranch          string
 	HeadCommitID        string `xorm:"-"`
 	BaseBranch          string
-	MergeBase           string `xorm:"VARCHAR(40)"`
+	MergeBase           string `xorm:"VARCHAR(64)"`
 	AllowMaintainerEdit bool   `xorm:"NOT NULL DEFAULT false"`
 
 	HasMerged      bool               `xorm:"INDEX"`
-	MergedCommitID string             `xorm:"VARCHAR(40)"`
+	MergedCommitID string             `xorm:"VARCHAR(64)"`
 	MergerID       int64              `xorm:"INDEX"`
 	Merger         *user_model.User   `xorm:"-"`
 	MergedUnix     timeutil.TimeStamp `xorm:"updated INDEX"`

models/issues/review.go

@@ -116,7 +116,7 @@ type Review struct {
 	Content          string `xorm:"TEXT"`
 	// Official is a review made by an assigned approver (counts towards approval)
 	Official  bool   `xorm:"NOT NULL DEFAULT false"`
-	CommitID  string `xorm:"VARCHAR(40)"`
+	CommitID  string `xorm:"VARCHAR(64)"`
 	Stale     bool   `xorm:"NOT NULL DEFAULT false"`
 	Dismissed bool   `xorm:"NOT NULL DEFAULT false"`