[Task] Add YAML Formatter to ensure GitHub Actions configuration can be loaded

[oliverholworthy]

Description

When making changes or adding new GitHub Actions Workflows to our projects. Without a check for valid YAML files, we can end up in situations where we're puzzled about why a workflow doesn't show up as a job in a Pull Request list of Actions.

Adding a YAML formatter, reduces this risk and saves time by preventing formatting errors from showing up in our configuration.

Proposed YAML formatter: Prettier. This one of the most widely used YAML formatters and adopted by tools like the YAML vs Code Extension

• Dataloader Add Prettier formatter for YAML and Markdown dataloader#73
• NVTabular Add Formatter (Prettier) for YAML and Markdown files NVTabular#1733
• Transformers4Rec
• Merlin
• Systems Add Prettier YAML/Markdown formatter to the linters systems#273
• Core Add Formatter (Prettier) for YAML and Markdown files core#199
• Models Configure Prettier YAML/Markdown formatter for all files models#1121