Feat: improve message when no models are ready to run

[treysp]

This PR updates the message displayed when the sqlmesh run command is executed but no models are ready to run.

The new message includes the time when the next model will be ready to run in UTC and local timezone.

Old output

Run finished for environment 'prod'

New output

No models are ready to run. Please wait until a model `cron` interval has elapsed.

Next run will be ready at 2024-12-13 6:00PM CST (2024-12-14 12:00AM UTC).

Implementation details:

• Variable capturing run completion status changed from boolean to ternary ENUM success/failure/nothing to do
• Start of next ready interval calculated as minimum over all models' interval_unit.cron_next(now())

[sungchun12]

Love the formatting of the message. I bet some users will want the ability to configure the local timezone, but not needed for this PR.