auth_token cached token handling

auth_token handles tokens that are from its cache, uncached PKI
(compressed and ASN, "offline validation") and UUID/hashed tokens
("online" validation).

For all of these cases, the auth_token middleware was doing

1) expiration check
2) confirm token bind
3) store in cache

In some cases, some of these steps aren't necessary.

When getting the token from the cache
1) no expiration check is needed because the expiration time is
   stored as cache data and the token would be rejected during
   _cache_get.
2) Storing in the cache is unnecessary because the token is
   already in the cache.

When doing online validation, it's not necessary to do the
expiration check because the identity server would have rejected
the token if it was expired.

Closes-Bug: #1289075
Change-Id: I6afa98504215521538434f1f8a2d97585ce35de5
Merge "auth_token cached token handling"