Adjust object format interface (#28469)

- Remove `ObjectFormatID`
- Remove function `ObjectFormatFromID`.
- Use `Sha1ObjectFormat` directly but not a pointer because it's an
empty struct.
- Store `ObjectFormatName` in `repository` struct

modules/git/parse_nogogit_test.go

@@ -12,7 +12,7 @@ import (
 )
 
 func TestParseTreeEntriesLong(t *testing.T) {
-	objectFormat := ObjectFormatFromID(Sha1)
+	objectFormat := Sha1ObjectFormat
 
 	testCases := []struct {
 		Input    string
@@ -66,7 +66,7 @@ func TestParseTreeEntriesLong(t *testing.T) {
 }
 
 func TestParseTreeEntriesShort(t *testing.T) {
-	objectFormat := ObjectFormatFromID(Sha1)
+	objectFormat := Sha1ObjectFormat
 
 	testCases := []struct {
 		Input    string
@@ -102,7 +102,7 @@ func TestParseTreeEntriesShort(t *testing.T) {
 
 func TestParseTreeEntriesInvalid(t *testing.T) {
 	// there was a panic: "runtime error: slice bounds out of range" when the input was invalid: #20315
-	entries, err := ParseTreeEntries(ObjectFormatFromID(Sha1), []byte("100644 blob ea0d83c9081af9500ac9f804101b3fd0a5c293af"))
+	entries, err := ParseTreeEntries(Sha1ObjectFormat, []byte("100644 blob ea0d83c9081af9500ac9f804101b3fd0a5c293af"))
 	assert.Error(t, err)
 	assert.Len(t, entries, 0)
 }