[git] IDEA-133726 refresh .git after fetch

refreshing will cause update(), but additionally will capture
changes which are not tracked by update(), e.g. in refs/tags/

(cherry picked from commit 227c3a83fa9d06ef5ebe7f11eeb04d17c12a460b)
[vcs] IDEA-133826 Fix wording

(cherry picked from commit e5a4e2dbd9c5b45598d2426fbb2b7b44e064924e)
[vcs] IDEA-131944 Fix grammar/wording in TODO checkin handler

(cherry picked from commit d662e61f1af3b4189ab6332a71edb2d41741ec3e)