[CHORE] Drop go-git support

See https://codeberg.org/forgejo/discussions/issues/164 for the
rationale and discussion of this change.

Everything related to the `go-git` dependency is dropped (Only a single
instance is left in a test file to test for an XSS, it requires crafting
an commit that Git itself refuses to craft). `_gogit` files have
been removed entirely, `go:build: !gogit` is removed, `XXX_nogogit.go` files
either have been renamed or had their code being merged into the
`XXX.go` file.

modules/git/tree_entry.go

@@ -8,8 +8,98 @@ import (
 	"io"
 	"sort"
 	"strings"
+
+	"code.gitea.io/gitea/modules/log"
 )
 
+// TreeEntry the leaf in the git tree
+type TreeEntry struct {
+	ID ObjectID
+
+	ptree *Tree
+
+	entryMode EntryMode
+	name      string
+
+	size     int64
+	sized    bool
+	fullName string
+}
+
+// Name returns the name of the entry
+func (te *TreeEntry) Name() string {
+	if te.fullName != "" {
+		return te.fullName
+	}
+	return te.name
+}
+
+// Mode returns the mode of the entry
+func (te *TreeEntry) Mode() EntryMode {
+	return te.entryMode
+}
+
+// Size returns the size of the entry
+func (te *TreeEntry) Size() int64 {
+	if te.IsDir() {
+		return 0
+	} else if te.sized {
+		return te.size
+	}
+
+	wr, rd, cancel := te.ptree.repo.CatFileBatchCheck(te.ptree.repo.Ctx)
+	defer cancel()
+	_, err := wr.Write([]byte(te.ID.String() + "\n"))
+	if err != nil {
+		log.Debug("error whilst reading size for %s in %s. Error: %v", te.ID.String(), te.ptree.repo.Path, err)
+		return 0
+	}
+	_, _, te.size, err = ReadBatchLine(rd)
+	if err != nil {
+		log.Debug("error whilst reading size for %s in %s. Error: %v", te.ID.String(), te.ptree.repo.Path, err)
+		return 0
+	}
+
+	te.sized = true
+	return te.size
+}
+
+// IsSubModule if the entry is a sub module
+func (te *TreeEntry) IsSubModule() bool {
+	return te.entryMode == EntryModeCommit
+}
+
+// IsDir if the entry is a sub dir
+func (te *TreeEntry) IsDir() bool {
+	return te.entryMode == EntryModeTree
+}
+
+// IsLink if the entry is a symlink
+func (te *TreeEntry) IsLink() bool {
+	return te.entryMode == EntryModeSymlink
+}
+
+// IsRegular if the entry is a regular file
+func (te *TreeEntry) IsRegular() bool {
+	return te.entryMode == EntryModeBlob
+}
+
+// IsExecutable if the entry is an executable file (not necessarily binary)
+func (te *TreeEntry) IsExecutable() bool {
+	return te.entryMode == EntryModeExec
+}
+
+// Blob returns the blob object the entry
+func (te *TreeEntry) Blob() *Blob {
+	return &Blob{
+		ID:      te.ID,
+		name:    te.Name(),
+		size:    te.size,
+		gotSize: te.sized,
+		repo:    te.ptree.repo,
+	}
+}
+
 // Type returns the type of the entry (commit, tree, blob)
 func (te *TreeEntry) Type() string {
 	switch te.Mode() {