[Bug report] Remove old applied themes

[JamyGolden]

Describe the bug

A type of feature request, even though it is a bug too.

When a theme is applied, it copies the themes from the templates to the data-dir. If the template is removed from tinty/config.toml, the theme files continue to live in the data dir, as well as the cloned repos. This doesn't cause an issue in most instances, but when the Sourcing scirpts that set env variables, this is an issue.

Expected behavior

Either make sure old files are cleaned out on apply/init or add a command that allows the user to "clean" the env with something like tinty clean or tinty clear