SidePanel: Migrate c/b/r/side_panel/customize_chrome to Lit, part 14.

In this part checking in the *.html.ts files for
  button_label.html
  cards.html
  hover_button.html
  shortcuts.html
  themes.html
  theme_snapshot.html

Bug: 40943652
Change-Id: I653e259eeb65b03ab8b5c42c99e7a8bc30921c10
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5537344


Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1300872}