Bluetooth: BAP: Unicast client Split start and connect

Removes the CIS connection establishment from bt_bap_stream_start
and move the behavior to a new funciton bt_bap_stream_connect.

This has 2 advantages:
1) The behavior of bt_bap_stream_start is much more clear and more aligned
with the spec's behavior for the receiver start ready opcode.
2) It is possible to connect streams in both the enabling
and the QoS configured state with bt_bap_stream_connect as
per the spec. This allows us to pass additional PTS test cases.

To implement this new behavior, samples and tests have been updated.

The CAP Initiator implementation has also been updated
to accomodate for the change in BAP, but the CAP
initiator implementation should work the same for application, except
that it's now possible to do unicast start on ASEs in any order
(https://github.com/zephyrproject-rtos/zephyr/issues/72138).

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>

doc/connectivity/bluetooth/api/audio/shell/bap.rst

@@ -34,6 +34,7 @@ Commands
       stream_qos             : interval [framing] [latency] [pd] [sdu] [phy] [rtn]
       qos                    : Send QoS configure for Unicast Group
       enable                 : [context]
+      connect                : Connect the CIS of the stream
       stop
       list
       print_ase_info         : Print ASE info for default connection
@@ -62,10 +63,8 @@ Commands
                                     [extended <meta>]
                                     [vendor <meta>]]
       send                   : Send to Audio Stream [data]
-      start_sine             : Start sending a LC3 encoded sine wave [all]
-      stop_sine              : Stop sending a LC3 encoded sine wave [all]
-      recv_stats             : Sets or gets the receive statistics reporting interval
-                              in # of packets
+      bap_stats              : Sets or gets the statistics reporting interval in # of
+                              packets
       set_location           : <direction: sink, source> <location bitmask>
       set_context            : <direction: sink, source><context bitmask> <type:
                               supported, available>
@@ -80,19 +79,19 @@ Commands
    "config","discover","idle/codec-configured/qos-configured","codec-configured"
    "qos","config","codec-configured/qos-configured","qos-configured"
    "enable","qos","qos-configured","enabling"
-   "[start]","enable","enabling","streaming"
+   "connect","qos/enable","qos-configured/enabling","qos-configured/enabling"
+   "[start]","enable/connect","enabling","streaming"
    "disable","enable", "enabling/streaming","disabling"
    "[stop]","disable","disabling","qos-configure/idle"
    "release","config","any","releasing/codec-configure/idle"
    "list","none","any","none"
    "select_unicast","none","any","none"
-   "connect","discover","idle/codec-configured/qos-configured","codec-configured"
    "send","enable","streaming","none"
 
 Example Central
 ***************
 
-Connect and establish a stream:
+Connect and establish a sink stream:
 
 .. code-block:: console
 
@@ -104,8 +103,9 @@ Connect and establish a stream:
    uart:~$ bap config sink 0
    uart:~$ bap qos
    uart:~$ bap enable
+   uart:~$ bap connect
 
-Or using connect command:
+Connect and establish a source stream:
 
 .. code-block:: console
 
@@ -113,8 +113,12 @@ Or using connect command:
    uart:~$ bap init
    uart:~$ bt connect <address>
    uart:~$ gatt exchange-mtu
-   uart:~$ bap discover sink
-   uart:~$ bap connect sink 0
+   uart:~$ bap discover source
+   uart:~$ bap config source 0
+   uart:~$ bap qos
+   uart:~$ bap enable
+   uart:~$ bap connect
+   uart:~$ bap start
 
 Disconnect and release:
 
@@ -479,8 +483,7 @@ parameters.
 Enable
 ******
 
-The :code:`enable` command attempts to enable the stream previously configured,
-if the remote peer accepts then the ISO connection procedure is also initiated.
+The :code:`enable` command attempts to enable the stream previously configured.
 
 .. csv-table:: State Machine Transitions
    :header: "Depends", "Allowed States", "Next States"
@@ -493,17 +496,33 @@ if the remote peer accepts then the ISO connection procedure is also initiated.
    uart:~$ bap enable [context]
    uart:~$ bap enable Media
 
-Start
-*****
+Connect
+*******
 
-The :code:`start` command is only necessary when acting as a sink as it
-indicates to the source the stack is ready to start receiving data.
+The :code:`connect` command attempts to connect the stream previously configured.
+Sink streams will have to be started by the unicast server, and source streams will have to be
+started by the unicast client.
 
 .. csv-table:: State Machine Transitions
    :header: "Depends", "Allowed States", "Next States"
    :widths: auto
 
-   "enable","enabling","streaming"
+   "qos/enable","qos-configured/enabling","qos-configured/enabling"
+
+.. code-block:: console
+
+   uart:~$ bap connect
+
+Start
+*****
+
+The :code:`start` command is only necessary when starting a source stream.
+
+.. csv-table:: State Machine Transitions
+   :header: "Depends", "Allowed States", "Next States"
+   :widths: auto
+
+   "enable/connect","enabling","streaming"
 
 .. code-block:: console
 

doc/releases/migration-guide-3.7.rst

@@ -447,6 +447,10 @@ Bluetooth Audio
   This needs to be added to all instances of CAP discovery callback functions defined.
   (:github:`72797`)
 
+* :c:func:`bt_bap_stream_start` no longer connects the CIS. To connect the CIS,
+  the :c:func:`bt_bap_stream_connect` shall now be called before :c:func:`bt_bap_stream_start`.
+  (:github:`73032`)
+
 * All occurrences of ``set_sirk`` have been changed to just ``sirk`` as the ``s`` in ``sirk`` stands
   for set. (:github:`73413`)