Rename files to preserve history

Test\Eslint fail - this is expected.

Change-Id: Ie38e5281a44481c051fb84d921767f317cadef04
diff --git a/polygerrit-ui/app/elements/admin/gr-plugin-list/gr-plugin-list.js b/polygerrit-ui/app/elements/admin/gr-plugin-list/gr-plugin-list.ts
similarity index 100%
rename from polygerrit-ui/app/elements/admin/gr-plugin-list/gr-plugin-list.js
rename to polygerrit-ui/app/elements/admin/gr-plugin-list/gr-plugin-list.ts