Ensure that group names are encoded in the Gnus registry file

* lisp/gnus/gnus-registry.el (gnus-registry--munge-group-names): New
  function for either encoding names (while saving) or decoding
  them (while reading).
  (gnus-registry-fixup-registry, gnus-registry-read): Use in these two
  locations.
1 job for scratch/gnus-decoded in 53 minutes and 54 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #2241
test-all

00:53:54