Add Enable/Disable flag for schedules

[jnewbigin]

If you have a scheduled build (eg. a Daily Build) but you don't want to run it for a few days, it would be ideal to set it to disabled so when you are ready to re-enable it, you don't need to remember all the settings (as you would have to do if you delete and re-create the schedule)

[felixfbecker]

I believe this is supported

UI:

GraphQL API:

[jnewbigin]

Looks good.

[toolmantim]

Oh yep, this is live and shipped! 🎉 Thanks @felixfbecker.

Sorry we didn't update this issue earlier @jnewbigin!