[Comparison Dashboard] Run dashboard.py validate as a part of CI

[JakeDern]

Pre-filing checklist

• I searched existing issues and didn't find a duplicate

Component(s)

Other

Objective

It's possible to check in bad manifest changes for the comparison dashboard with dangling references to files etc. These can be checked with the dashboard validate command.

Rationale

Avoid obvious mistakes when updating the dashboard metadata.

Scope

A dashboard.py validate is run on every PR. Fails if issues are detected, otherwise passes.

Acceptance Criteria

.

Dependencies or Blockers

No response

Additional Context

No response