Rename files to preserve history

Test\Eslint fail - this is expected.

Change-Id: I4093f48519e3762decaed45ee3fddaca587214f1
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list.js b/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list.ts
similarity index 100%
rename from polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list.js
rename to polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list.ts