Update the AccessTracker, WebAuthn handlers, and identity manager
refresh loop to perform their session record updates using the
databroker Patch() method.
This should prevent any of these updates from conflicting.
* session: add accessed at date
* authorize: track session and service account access times
* Revert "databroker: add support for field masks on Put (#3210)"
This reverts commit 2dc778035d.
* add test
* fix data race in test
* add deadline for update
* track dropped accesses
