Bluetooth: BAP: Unicast server depend on PACS

When in the BAP unicast server role, at least PAC sink
or PAC source shall be set.

In order to fulfill this new requirement, a few other Kconfig
options had to be changed to a `depends on` from `select` to
avoid recursive Kconfig requirements. This change may require
some applications to update their configurations according
to the migration guide.

The change from `select` to `depends on` is ideal anyhow
as that is the recommended way to add dependencies.

This can checked via the combined BT_PACS Kconfig value.

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