Include the CWT validation in VTS testing.

This change modifies the VTS tests to validate the structure of the CBOR
Web Token (CWT) which contains the public key as one of several fields
in the map. It only validates the subset of fields expected to be seen
in the VTS tests. The ones related to the actual BCC will not be
present in test mode due to the security guarantees of the interface.

Additionally, the test will also now check that the first key in the BCC
array matches the public key that should be self-signed in the
certificate located in the second index of the BCC array.

Test: atest VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I9e7769861529b8095d77ce8fee3c78222579d38c