Rename .gypi -> .gni. Rename and reformat all gyp files. They were previously converted to gn but not renamed to preserve continuity in git. This rename completes the removal of all traces of gyp. BUG=angleproject:1569 Change-Id: I50123105d8881583184ffc564bed65d9fbe4d41c Reviewed-on: https://chromium-review.googlesource.com/1187885 Commit-Queue: Frank Henigman <fjhenigman@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>