i18n: add translations

The pipewire.pot file is made with 'meson compile pipewire-pot' by
scanning the files in POTFILES.in.
The .po files were generated with 'meson compile pipewire-update-po',
on .po file per entry in LINGUAS.
The .po files were filled with:
'msgmerge -N $pulseaudio/po/$lang.po po/$lang.po -o po/$lang.po' to
get a decent set of translations for all the ACP strings.

Run 'LANGUAGE=nl make run' to start the server in a language,
test with 'LANGUAGE=nl pavucontrol'

po/LINGUAS

@@ -1,2 +1,50 @@
+af
+as
+be
+bg
+bn_IN
+ca
 cs
+da
+de_CH
+de
+el
+es
+fi
+fr
 gl
+gu
+he
+hi
+hr
+hu
+id
+it
+ja
+kk
+kn
+ko
+lt
+ml
+mr
+nl
+nn
+oc
+or
+pa
+pl
+pt_BR
+pt
+ru
+sk
+sr@latin
+sr
+sv
+ta
+te
+tr
+uk
+zh_CN
+zh_TW
+eo
+si