Renaming only hbs to gts does not work in `template-tag-codemod` `merge-history` command

[BoussonKarel]

I've found some issues in the merge-history command of the @embroider/template-tag-codemod, where the command does not work when you have only converted route templates (probably also an issue when you only convert components that are template only without JS/TS file).

Only HBS files were renamed to GTS files.

The CLI command also tries to commit the renaming of TS/JS to GTS files, but there are no such changes, so it changes.

[nickschot]

Also ran into this. I wonder if --allow-empty would be enough to fix it.