Rename files to preserve history

Test\Eslint fail - this is expected.

Change-Id: I14f8b4cc6c9cca009b937ba5614611a56ff883e0
diff --git a/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js b/polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts
similarity index 100%
rename from polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.js
rename to polygerrit-ui/app/elements/change/gr-file-list/gr-file-list.ts