Reduce calls to git cat-file -s (#14682)

* Reduce calls to git cat-file -s

There are multiple places where there are repeated calls to git cat-file
-s due to the blobs not being created with their size.

Through judicious use of git ls-tree -l and slight adjustments to the
indexer code we can avoid a lot of these calls.

* simplify by always expecting the long format

* Also always set the sized field and tell the indexer the update is sized

modules/git/parse_nogogit_test.go

@@ -0,0 +1,70 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+// +build !gogit
+
+package git
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseTreeEntries(t *testing.T) {
+
+	testCases := []struct {
+		Input    string
+		Expected []*TreeEntry
+	}{
+		{
+			Input: `100644 blob ea0d83c9081af9500ac9f804101b3fd0a5c293af    8218	README.md
+100644 blob 037f27dc9d353ae4fd50f0474b2194c593914e35    4681	README_ZH.md
+100644 blob 9846a94f7e8350a916632929d0fda38c90dd2ca8     429	SECURITY.md
+040000 tree 84b90550547016f73c5dd3f50dea662389e67b6d       -	assets
+`,
+			Expected: []*TreeEntry{
+				{
+					ID:        MustIDFromString("ea0d83c9081af9500ac9f804101b3fd0a5c293af"),
+					name:      "README.md",
+					entryMode: EntryModeBlob,
+					size:      8218,
+					sized:     true,
+				},
+				{
+					ID:        MustIDFromString("037f27dc9d353ae4fd50f0474b2194c593914e35"),
+					name:      "README_ZH.md",
+					entryMode: EntryModeBlob,
+					size:      4681,
+					sized:     true,
+				},
+				{
+					ID:        MustIDFromString("9846a94f7e8350a916632929d0fda38c90dd2ca8"),
+					name:      "SECURITY.md",
+					entryMode: EntryModeBlob,
+					size:      429,
+					sized:     true,
+				},
+				{
+					ID:        MustIDFromString("84b90550547016f73c5dd3f50dea662389e67b6d"),
+					name:      "assets",
+					entryMode: EntryModeTree,
+					sized:     true,
+				},
+			},
+		},
+	}
+	for _, testCase := range testCases {
+		entries, err := ParseTreeEntries([]byte(testCase.Input))
+		assert.NoError(t, err)
+		assert.EqualValues(t, len(testCase.Expected), len(entries))
+		for i, entry := range entries {
+			assert.EqualValues(t, testCase.Expected[i].ID, entry.ID)
+			assert.EqualValues(t, testCase.Expected[i].name, entry.name)
+			assert.EqualValues(t, testCase.Expected[i].entryMode, entry.entryMode)
+			assert.EqualValues(t, testCase.Expected[i].sized, entry.sized)
+			assert.EqualValues(t, testCase.Expected[i].size, entry.size)
+		}
+	}
+}