Minify cache tags sent in the header

Rebuild the patch for version 2.1.2

I can confirm that patch #4 works well and has solved my issue. Our large sites have dozens of menus, blocks, and paragraphs on most pages and these combine to raw un-minified Surrogate-Key lengths of well over 25,000 characters for 390 separate cache-tags. This patch brings that header size down to under 2,000 bytes.

I've attached a re-roll of #4 which applies to version 2.3.3 of the module.

Fixed two minor issues in the prior patch.