rate_limit: Add time unit week (#37494)

Following on from https://github.com/envoyproxy/envoy/pull/24070 and
adding support for week as a unit of time for ratelimits as this is
something my team currently needs and WEEK felt sad as it was missing
the protobuf party.

Ideally we would have something like
https://github.com/envoyproxy/envoy/issues/33277 but in the interim it
makes sense to add WEEK here since we have every other period already
except week.

Signed-off-by: Stefan Sedich <stefan.sedich@gmail.com>

Mirrored from https://github.com/envoyproxy/envoy @ 33fb49977a10657a84a4aff1ea8c7988c54e3c42

envoy/service/ratelimit/v3/rls.proto

@@ -94,6 +94,9 @@ message RateLimitResponse {
       // The time unit representing a day.
       DAY = 4;
 
+      // The time unit representing a week.
+      WEEK = 7;
+
       // The time unit representing a month.
       MONTH = 5;