feat: add new field source to Nova config

[amazeAmazing]

What's changing and why?

• Nova recipes are adding a new field called source under the run config to contain what source triggered the SMHP job for Nova models. I am adjusting the validation to accept this new field.

Before/After UX

Before:

User who pass a source field under run for Nova recipes failed validation.

After:

User who pass a source field under run for Nova recipes pass validation.

User experience will not change for users who directly use the Sagemaker Hyperpod CLI, as no recipes in the sagemaker-hyperpod-recipes package will change.

However, for customers who use the Nova Forge SDK, the Nova Forge SDK will populate this field in their recipe for SMHP Nova recipes.

How was this change tested?

Locally tested this change and validating that the training images supported this field.

Are unit tests added?

No

Are integration tests added?

No

Reviewer Guidelines

‼️ Merge Requirements: PRs with failing integration tests cannot be merged without justification.

One of the following must be true:

• All automated PR checks pass
• Failed tests include local run results/screenshots proving they work
• Changes are documentation-only