Add filter option to UserSelection to exclude blocked users

The patch don't apply to Core 10.3.1
The patch in comment #20 is already included in Core 10: https://api.drupal.org/api/drupal/core%21modules%21user%21src%21Plugin%2...

Rerolled patch for 10.3.2

The fix had not been included in core yet!

I applied the rerolled patch in #39, which still applies cleanly even to Drupal 10.3.6, and it worked fine, it just needs some clarification in the field help text imo..

When creating Entity reference fields on Users, this becomes the default:

You would assume from the description that the checked option will make users without the 'administer users' permission able to select blocked users. The opposite is true: the checked option, ie. by default, leaves core behaving like currently (you can't select blocked users unless you have the 'admin users' perm), but if unchecked it hides the blocked users on that field even to roles with the 'aminister users' permission.

So the feature is consistent with the original request, but we can improve the intuitiveness by reverting the label & description:

[ ] Exclude blocked users (unchecked by default - also, leave the "Include the anonymous user." as independent of this option)
Even if this option is not set, only users with the administer users permission may (view and) reference blocked users.

Changes are made on on 11.x (our main development branch) first, and are then back ported as needed according to our policies.