Bluetooth: Mesh: Add proxy send callback

Zephyr Bluetooth Mesh did not check whether the proxy message
was actually sent out, so that the response message could
not be received during reset. It did not solve the status
callback of the proxy sending message, so a new problem was
introduced after PR(#28457) merged.

bt_mesh_prov_send(&buf, public_key_sent))

This PR will try to solve the above problem, and will fix
the problem due to thread competition, and PR(#26668) will
not be necessary.

Compared with PR(#30138), it no longer consumes extra RAM
space and supports synchronization of group addresses

Signed-off-by: Lingao Meng <menglingao@xiaomi.com>