Rename files to preserve history

Test\Eslint fail - this is expected.

Change-Id: Iec00b90c4b3ea2fc853c1c49cf3707f309c9ce08
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.js b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts
similarity index 100%
rename from polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.js
rename to polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts