refactor!: remove go-git backend (#39487)

Removes the go-git backend so every build uses the git CLI backend. Its
Windows performance advantage is gone, it lacks SHA-256 support, and it
breaks repositories on Windows.

The performance changes moved to
https://github.com/go-gitea/gitea/pull/39526.

Fixes https://github.com/go-gitea/gitea/issues/38359
Fixes https://github.com/go-gitea/gitea/issues/34694

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/git/last_commit_cache.go

@@ -78,3 +78,43 @@ func (c *LastCommitCache) GetCommitByPath(ctx context.Context, entryCommitID Obj
 
 	return lastCommit, nil
 }
+
+// CacheCommit will cache the commit from the gitRepository
+func (c *Commit) CacheCommit(ctx context.Context, gitRepo *Repository) error {
+	return c.recursiveCache(ctx, gitRepo, c.Tree(), "", 1)
+}
+
+func (c *Commit) recursiveCache(ctx context.Context, gitRepo *Repository, tree *Tree, treePath string, level int) error {
+	if level == 0 {
+		return nil
+	}
+	entries, err := tree.ListEntries(ctx, gitRepo)
+	if err != nil {
+		return err
+	}
+
+	entryPaths := make([]string, len(entries))
+	for i, entry := range entries {
+		entryPaths[i] = entry.Name()
+	}
+
+	_, err = walkGitLog(ctx, gitRepo, c, treePath, entryPaths...)
+	if err != nil {
+		return err
+	}
+
+	for _, treeEntry := range entries {
+		// entryMap won't contain "" therefore skip this.
+		if treeEntry.IsDir() {
+			subTree, err := tree.SubTree(ctx, gitRepo, treeEntry.Name())
+			if err != nil {
+				return err
+			}
+			if err := c.recursiveCache(ctx, gitRepo, subTree, treeEntry.Name(), level-1); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}