Add rule to validate AWS::Events::Rule ScheduleExpression

[fatbasstard]

Just spent way too much time on deploying a scheduled Lambda... The ScheduledExpression can be a Cron, but it's not really a normal Cron 🤔 (When using an online Cron tool at least).

The creating of the Sceduled event in the Lambda console is also not helping, since it validates the Cron at "Save" (try it, it's a lot of clicking to get an error.. Which you cannot easily edit 😛 )

Can we add this check to a new rule (or an existing one if we have one that fits)?

Sample Expression that breaks:

cron(0 */1 * * MON)

Sample Expression that's correct:

cron(1 * ? * MON *)

Documentation: https://docs.aws.amazon.com/lambda/latest/dg/tutorial-scheduled-events-schedule-expressions.html

[PatMyron]

Another AWS::Events::Rule.ScheduleExpression request

Another AWS::Events::Rule.ScheduleExpression request

existing AWS::Events::Rule.ScheduleExpression rule

[kddejong]

There is a lot here to validate. Starting with the validation that Day-of-month or Day-of-week have a question mark. Not sure how much farther down this path I want to go now or continue to take it based on request.