environment: Bufferize the single audio frames

This improves the performances significantly in cores sending single
audio samples rather than batches, as sending them in batches avoids
emitting many costly signals stupidly often.

Fixes #20
2 jobs for master in 5 minutes and 21 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #213104
flatpak:demo

00:01:51

 
  Test
passed #213105
flatpak:tests

00:03:29