Proposal: Add a separate “flatpaks/” namespace.

Currently, the content for a Flatpak in Fedora can be found in
modules/<application>. E.g.:
<a href="" title=""></a> - I’d
like to propose creating a separate namespace in
- flatpaks/

* Allow automation to easily distinguish Flatpaks from other modules.
(<a href=" ... at lists dot" title=" ... at lists dot"> ... at lists dot fedoraproject....</a>
* Make it easy to browse through the source of available Flatpaks
* Reduce some confusion. A Flatpak is a module, but it’s *also* a
container, and the dist-git repository will include files for both.

* We have a few graphical applications that are available as standard
loose-rpm macros (gimp, rawtherapee, skychart). While it should work
to have flatpaks/gimp and modules/gimp build different streams of the
gimp module, it’s going to be more confusing than different branches
in the same repository. (There are even possibilities for using the
*same* branch using module-stream-expansion, though that’s not
something I’d encourage at the moment.)

Needed steps:
* Remove special casing of flatpak => modules in Bodhi
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* Adjust namespace special-casing in fedpkg
<a href="" title=""></a>
* Adjust namespace special-casing in fedscm_admin
<a href="" title=""></a>
* In fedscm_admin: Map flatpaks namespace to the ‘module’ PDC branch
type when storing the SLA into the PDC, to avoid PDC changes, and
because the SLA really is a module SLA.
* Adjust distgit pagure configuration to add flatpaks to
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* Add flatpaks/ to the kojid allowed_scms configuration
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* Add flatpaks/ to the module-build-service SCMS configuration
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* Adjust the owner-sync-pagure script to handle flatpaks/
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* Move or reimport existing Flatpak repositories
(modules/eog, modules/feedreader, modules/flatpak-common,
modules/gnome-clocks, modules/gnome-tetravex, modules/quadrapassel)

Potential issues:
* We should probably move flatpak-common to the flatpaks/ namespace
for ease of discovery, but it isn’t in any way a flatpak, it’s just a
module that Flatpaks can depend on.
* The ability of modules to include other modules won’t work without
further adjustments to the MBS (MODULES_ALLOW_REPOSITORY) -
I don't see this as useful functionality for Flatpaks.