[uwb-core] Add support support for custom vendor message type

Vendor uci commands can now send messages with type testing_1
and testing_2 which are reserved for testing. FiRa CR-435.

Bug: 261377401
Test: atest libuwb_core_tests, atest libuwb_uci_packet_tests
Change-Id: I72cdcec5115e47a01e4e5a5f72af00ae2617eb4d
11 files changed