Lock interface & Context argument

[agcom]

The Redis-lock methods do not receive a context argument; the merged PR #652 did a trick of passing the Redis client's context to its own methods' calls, which I strongly doubt its impact. Moving on, go-redis was updated to v9 on #793; the new client removed access to its maybe internal context; therefore, the below line was commented.

machinery/v1/locks/redis/redis.go

Line 68 in 0c29c70

// ctx := r.rclient.Context()

I guess that the lock interface methods should receive a context argument to possibly cancel the lock operation, specially in case the Redis calls take too much time; what are your thoughts?