These aliases (`map[string]string` and `map[gid.GID]Attributes`) give
batch authorization call sites readable types when loading and
returning per-resource condition attributes. ConditionContext now uses
the alias instead of the bare map type, with no behavior change.
Also extend policy tests to cover ResourcePattern.MatchesResource,
comma-separated value handling for In/NotIn, unresolved-reference
fallthrough, and resolveKey/resolveValue.
Signed-off-by: Bryan Frimin <bryan@probo.com>
