Bluetooth: SDP: Get ProtocolDescriptorList attribute internals

Adds API to get available specific information included in protocols UUID
tree during parsing Protocol Descriptor List attribute. Usually it's to
be remote Server Channel/PSM number operating on applicable protocol.
There're a few helper functions added to be able parse and retrieve such
information from raw record data.

Jira: ZEP-1112

Change-Id: I736a780b95ba54821d36e6011b739f5ff37cd64f
Signed-off-by: Arkadiusz Lichwa <arkadiusz.lichwa@tieto.com>