Backport the CI workflow from the main branch, including scripts,
but fix the image version at fedora:40.

Refactor the Nextcloud/ownCloud auto-configuration to work like the
preconfig function for Fastmail/mailbox.org.

When ensuring credentials or refreshing an account, run the credential
check on the first available endpoint rather than misusing the `Uri`
field.

This had been found by Coverity Scan as:

   src/goabackend/goautils.c:675:7: overwrite_var: Overwriting "error_msg" in
   "error_msg = g_strdup_inline((char *)g_dgettext("gnome-online-accounts", "Not found"))"
   leaks the storage that "error_msg" points to.

which happened, because the missing `break` falls through to the next case.

Drop the post-discovery identity and presentation identity hacks.

Backports for GNOME 46

See merge request GNOME/gnome-online-accounts!254

Allow editing the username and server for Exchange accounts when
refreshing credentials.

closes #80

Properly store and reset the SSL/TLS error override in the
WebDAV and Exchange providers.