Add NvimTreeFolder* For SCM Status

[alex-courtis]

Discussed in #2196

^{Originally posted by Machine-Maker May 8, 2023}
Afaik, there isn't a setting to differentiate the git_highlight between files and folders. It'd be nice to be able to configure those separately. In fact, I think quite a few of the settings would benefit from having the ability to configure files and folders separately.

[alex-courtis]

That is possible, perhaps NvimTreeFolderDirty, NvimTreeFolderStaged etc.

Simplest to link those both to NvimTreeGitDirty etc.