Move authz result logging to common place.
Prior to this change, the final result is not logged when
fallback to the default authorization.no_match config value.
Aso, if the result is provided by a hook callback,
it's also not logged.
After this change, only the final result is logged.
The authz chain resutls can be traced (or logged at debug level).
Even though most of the time these modules will be used by
connectors, there are exceptions (namely, `emqx_rule_engine`).
Besides, they are general enough to land there, more so given
that `emqx_placeholder` is already there.
This slightly changes semantics: now the attempt to create authenticator
with illegal bindings in templates will fail, instead of treating them
as literals. The runtime behaviour on the other hand should be the same.
Zaiming (Stone) Shi