fix(gha): Gracefully handle bad GHA job definitions

[nimrodkor]

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Description

Allow GHA checks to gracefully handle bad job definitions.
Also add GHA to the PR title check

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my feature, policy, or fix is effective and works
• New and existing tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Eliran-Turgeman]

Instead of adding safety measures inside the checks, can we apply it as a rule for the schema validation? (checkov/github_actions/schema_validator.py)

[nimrodkor]

@Eliran-Turgeman Tried that, didn't have much luck 😓