Fix incorrect file links (#34189)

Fix #34188

The name "FileName" is ambiguous: sometimes it is "base name without
path", sometimes it is "full name with path".

The ambiguous name causes various problems.

This PR clarifies the usage: `FileTreePath`: the full name with path.

templates/repo/blame.tmpl

@@ -10,7 +10,7 @@
 		</div>
 	{{end}}
 {{end}}
-<div class="{{TabSizeClass .Editorconfig .FileName}} non-diff-file-content">
+<div class="{{TabSizeClass .Editorconfig .FileTreePath}} non-diff-file-content">
 	<h4 class="file-header ui top attached header tw-flex tw-items-center tw-justify-between tw-flex-wrap">
 		<div class="file-header-left tw-flex tw-items-center tw-py-2 tw-pr-4">
 			{{template "repo/file_info" .}}