This PR fixes file name coloring in the project panel and tabs when
.gitignore file is updated. It's intended to fix #7831.

There's another, less vivid, problem with git-aware labels coloring.
It's about files that are both ignored and contained in the git index.
I'll file a separate issue for it to keep this fix focused.

Release Notes:

- Fixed file Git status refreshing on .gitignore update (#7831).