Refactor token and map parsing

The aim of this change is to make it possible to verify nested EATs.
This requires finer grade control over how the token structure is
parsed, as CBOR envelopes can now be present inside the tree.

So this change makes the parsing the token and the map a recursive
operation, calling the necessary methods of the objects at each level.

Change-Id: I4c1e29deae7b238f2d82a73bd95c533f89492d40
Signed-off-by: Mate Toth-Pal <mate.toth-pal@arm.com>
9 files changed