Merge branch 'cc/untracked'

Update the untracked cache subsystem and change its primary UI from "git update-index" to "git config". * cc/untracked: t7063: add tests for core.untrackedCache test-dump-untracked-cache: don't modify the untracked cache config: add core.untrackedCache dir: simplify untracked cache "ident" field dir: add remove_untracked_cache() dir: add {new,add}_untracked_cache() update-index: move 'uc' var declaration update-index: add untracked cache notifications update-index: add --test-untracked-cache update-index: use enum for untracked cache options dir: free untracked cache when removing it