samples: Bluetooth: Refactor TX for unicast audio client

Refactored the unicast audio client sample to use a
separate thread for TXing, rather than the system workqueue.

This allows us to do blocking waiting operations like
buf = net_buf_alloc(&tx_pool, K_FOREVER);
and also splits the responsibility of TXing to a new
file as well.

LC3 handling have also been moved to a new file, so
that it does not pollute the source code for non-LC3
supported builds. This also fixes various issues and
improves the LC3 handling in the sample.

Signed-off-by: Emil Gydesen <[email protected]>

Author: Thalley

samples/bluetooth/bap_unicast_client/CMakeLists.txt

@@ -8,4 +8,7 @@ target_sources(app PRIVATE
   src/main.c
 )
 
+zephyr_sources_ifdef(CONFIG_LIBLC3 src/stream_lc3.c)
+zephyr_sources_ifdef(CONFIG_BT_AUDIO_TX src/stream_tx.c)
+
 zephyr_library_include_directories(${ZEPHYR_BASE}/samples/bluetooth)