Transcoding at lower bitrate for limited bandwidth (#58)

Hello!

To begin with, thanks a lot for Funkwhale and the Android application, which is delightful to use every day.

As mentioned in #58, the application does not yet have a way to reduce the amount of data exchanged between the player and the server. When streaming high-quality audio on 4G or 5G connection, it can get very costly if one does consume a lot of FLAC content. This PR is an attempt at solving this issue and is my first contribution to the project. I would appreciate some hints/helps according to unit tests, translations, and probably things I did not cover for the moment...

Here is a summary of what I have done:

• Add a new setting called "Bandwidth limitation" with an icon, and a basic description,
• If bandwidth limitation is set to limited, append &to=mp3&max_bitrate=320 to the listen URL of the candidate best track upload.

A better way to do it in the future would be to add a bar to configure the desired maximum bitrate, and probably check in the cache if the best upload is already there before asking for a reduced one. Testing that the best quality upload is already meeting the bandwidth constraint would be interesting to avoid an unneeded transcoding on the server side. I prefer to point out the flaws so that we can discuss about them together! 😄

Thank in advance,

Dylan

app/src/main/res/values-ca/strings.xml

@@ -19,6 +19,11 @@
     <string name="settings_media_quality_quality">Qualitat màxima</string>
     <string name="settings_media_quality_size">Mida més petita</string>
     <string name="settings_media_quality_summary_quality">Es reproduirà la millor versió disponible</string>
+    <string name="settings_bandwidth_limitation">Limitació d\'ample de banda</string>
+    <string name="settings_bandwidth_limitation_unlimited">Il·limitat</string>
+    <string name="settings_bandwidth_limitation_limited">Limitat</string>
+    <string name="settings_bandwidth_limitation_summary_unlimited">El contingut original es recuperarà sense transcodificar</string>
+    <string name="settings_bandwidth_limitation_summary_limited">Endpoint oferirà contingut que respecti la taxa de bits màxima de 320 kbps</string>
     <string name="settings_media_cache_size">Mida de la memòria cau dels mitjans</string>
     <string name="settings_play_order">Ordre de reproducció preferit</string>
     <string name="settings_play_order_shuffle">Àlbums aleatoris</string>