In this commit, we update our various firewall interceptors so that they
rely on the session ID passed via gRPC metadata to extract a session ID.
For the PrivacyMapper and RuleEnforcer, these _MUST_ always contain a
session ID and so we error out if one was not found. For the request
logger, the session ID is optional and so we pass it to the new
SessionID field in the AddActionReq - our bbolt actions DB will not make
use of this field on persistence (but our incoming SQL version will).
Update the PrivacyMapDB interface methods to take contexts (both the
methods themselves and the call-back params) and then ensure all
implementations are updated and all call-sites pass contexts through
correctly.
We pass a random lnd connection identifier to the rule enforcer that is
unique per lnd connection lifetime. It is used to generate unique
request identifiers that amend the non-unique request identifiers that
are passed from lnd.
SessionDB is an interface that gives helper methods for how privacy
mapping should be done. A mock for SessionDB is added to save on some
code repetition, the privacy flags functionality is used in a later
test.
