runtime(debian): update debian related runtime files (#13423)

* Update Debian runtime files

Add mantic as a supported Ubuntu release and move buster/kinetic to
unsupported.

Add syntax highlighting for deb822sources filetype.

Add debsources ftplugin to set relevant comment options.

Move common version information to shared/debversions.vim

Closes #11934

Co-authored-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Co-authored-by: James Addison <jay@jp-hosting.net>
Co-authored-by: Viktor Szépe <viktor@szepe.net>
Signed-off-by: James McCoy <jamessan@jamessan.com>

* Add myself as codeowner for Debian-related runtime files

Signed-off-by: James McCoy <jamessan@jamessan.com>

---------

Signed-off-by: James McCoy <jamessan@jamessan.com>
Co-authored-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Co-authored-by: James Addison <jay@jp-hosting.net>
Co-authored-by: Viktor Szépe <viktor@szepe.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/ftplugin/debchangelog.vim

@@ -3,7 +3,7 @@
 " Maintainer:   Debian Vim Maintainers <team+vim@tracker.debian.org>
 " Former Maintainers:   Michael Piefel <piefel@informatik.hu-berlin.de>
 "                       Stefano Zacchiroli <zack@debian.org>
-" Last Change:  2023 Jan 16
+" Last Change:  2023 Aug 18
 " License:      Vim License
 " URL:          https://salsa.debian.org/vim-team/vim-debian/blob/main/ftplugin/debchangelog.vim