Add New Feature File finder(recreate - #9855)

Using the regular expression, develop "file finder" feature. (http://feedback.gitlab.com/forums/176466-general/suggestions/4987909-add-file-finder-fuzzy-input-in-files-tab-to-ju)

Issue(#9854)

1. apply ajax request
2. fuzzy filter(https://github.com/jeancroy/fuzzaldrin-plus)
3. short cut(when "t" was hitted, go to 'file find' page and 'esc' is to go back)

(ps. cause by my mistake, recreate PR, sorry!!)