It got renamed in f6f9e3f0

Fixes #200

Added callaudiod to the Flatpak manifest so Calls builds again.

It got moved in f6f9e3f0

This makes sure we valiate desktop files

If there are translation in C files but not in POTFILES.in
fail the pipeline.

It has translatable strings.

In libhandy 1, the hdykeypad CSS class name got renamed into keypad, and
HdyKeypad isn't a GtkGrid anymore but it contains one.

Bumping the max version gets rid of a build warning introduced in MR
!136

Now that we got rid of ugly hacks, these buttons should work on all
devices. We can therefore enable them by default.

`callaudiod` is a device-agnostic service for routing audio during voice
calls, called through `libcallaudio`.

It allows us to automatically switch profiles when entering a call,
enable the speaker output or mute the microphone, and can therefore be
used to replace the current Librem 5-specific hacks.

This is needed to be able to use callaudiod before it reaches
Debian Bullseye.

This commit aims to close #183