Rename files to preserve history

Test\Eslint fail - this is expected.

Change-Id: I0b7356079c6ca0daf767c708449c7b377c2409c6
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
similarity index 100%
rename from polygerrit-ui/app/elements/shared/gr-comment/gr-comment.js
rename to polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts