Update the bundled RRSSB library

Title: Update the bundled RRSSB library, and decide whether
to stay on it

Problem/Motivation

The module bundles RRSSB in
js/rrssb.min.js and css/rrssb.css, and
sharerich.libraries.yml declares it as version
1.8.4. Three things are wrong with that:

• The bundled files do not match the version we claim.
  Upstream v1.8.4 ships a 4,989 byte
  rrssb.min.js and an 11,079 byte rrssb.css; we ship
  5,528 and 7,668. So the declared version is not a reliable statement of what
  is actually in the repository, and there is no record of what was changed or
  why.
• It is six releases behind. The last upstream release is
  1.14.0.
• Upstream is dormant. 1.14.0 was published in
  February 2017 and the last commit to the repository was October 2020. It is
  not archived, but there has been no activity in about six years and 25
  issues are open.

Separately, RRSSB is a jQuery plugin, so
sharerich.libraries.yml depends on core/jquery.
Drupal core has been steadily removing its own jQuery use, and a share-button
widget is not a strong reason for a site to keep loading it.

Proposed resolution

In order:

1. Establish what we actually ship. Diff the bundled files
   against each upstream tag to find the real base version, and work out
   whether the differences are deliberate patches worth keeping.
2. Update to 1.14.0 >, re-applying anything found in step 1 that is still needed, and correct
   the version in sharerich.libraries.yml so it is
   honest.
3. Decide whether to stay on RRSSB at all. Given it has been
   dormant since 2020 and pulls in jQuery, it is worth asking whether the
   responsive resize behaviour it provides is worth the dependency, or whether
   it could be replaced with a small amount of modern CSS and vanilla JS. That
   would drop core/jquery from the library definition.

Remaining tasks

• Identify the true base version of the bundled files.
• Update, or replace, with the buttons still rendering correctly on Drupal 9,
  10, 11 and 12.
• Check the button layout still reflows at narrow widths, which is the whole
  point of the library.