Fix: overrides handle relative paths as expected (fixes #11577)

[mysticatea]

What is the purpose of this pull request? (put an "X" next to item)

[X] Bug fix #11577

What changes did you make? (Give an overview)

This PR fixes overrides[].files and overrides[].excludedFiles to handle ./ as expected.

The change is below. Especially, we newly can specify ./*.js-like patterns that match with the files in the root directory but not in subdirectories.

Pattern	FilePath	Before	After	Fixed
*.js	foo.js	true	true
*.js	dir/foo.js	true	true
./*.js	foo.js	false	true	✅
./*.js	dir/foo.js	false	false
dir/*.js	foo.js	false	false
dir/*.js	dir/foo.js	true	true
./dir/*.js	foo.js	false	false
./dir/*.js	dir/foo.js	false	true	✅

Is there anything you'd like reviewers to focus on?

Nothing in particular.

[platinumazure]

LGTM, thanks!

[g-plane]

LGTM, thanks!

[aladdin-add]

LGTM, thanks!