Bluetooth: Mesh: Implement Bridge Config Client

Implements the Bridge Configuration Client model.
Adds opcodes for all Bridge messages to `foundation.h`. Adds client-side
support for these messages.
Adds a new Kconfig option for the Bridge Configuration Client model to
configure the waiting time for respones for acked messages.

Signed-off-by: Håvard Reierstad <haavard.reierstad@nordicsemi.no>