feat(ci): Add check to ensure go fmt has been ran

[rwjblue-glean]

Motivation and Context

I noticed that some of the files weren't formatted (go fmt left dirty files on main), so I went ahead and added a lint CI job. We can add more linting things later if folks want, but validating formatting seemed like a nice first step.

I pushed a separate commit with go fmt ./... ran alone (just to make it clear what was automated changes vs manual ones).

How Has This Been Tested?

N/A

Breaking Changes

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[findleyr]

Thanks! We're actually pretty naive to GitHub actions (we have our own CI system for the Go project). Much appreciated.

[rwjblue-glean]

I've done a ton with GHA over the years, happy to help add anything y'all find useful (e.g. golangci-lint setup).