feat(AWS Schedule): Support groupName for scheduler method

[mzl-md]

Closes: #12319

Allows users to specify a schedule group for schedule events with method scheduler in AWS.

For convenience, we could create a schedule group, if none with the given name exists, rather than relying on the user to create one as a resource. Since I believe the common use case is to have more than one schedule in the same group, referring to the group as !Ref SchedulerGroup should be preferred and that is cleaner when users define the group themselves.

[bartelemi]

Amazing, something like this would be really helpful 👌