Add some automation around checking commit style

[vadasambar]

Problem statement.
Some of the contributors to datadog-service haven't contributed to Keptn before so they usually don't know the commit and the PR style we follow. We have to tell them about this when they make their first PR.

Describe the solution you'd like
It'd be nice to have an automated check for commit and PR style. It could be a github workflow on PRs. The check should also suggest the right way to do things (i.e., how to fix the current commit or PR)

Additional context
We have a similar check in Keptn for PR titles (we use this github action for that)

TODO

• Add PR title check
• Add PR commit check
• Make sure they work (screenshots or something else which makes it easier to review)
• Raise a PR and get it reviewed
• DONE

[vadasambar]

If you need help or clarification on the issue, please comment here or reach out to @vadasambar in Keptn slack.

[tarangverma]

can i take up this issue

[tarangverma]

additionally: can we add contributing guide to this repo is it a good option..

[vadasambar]

@tarangverma I am open to the idea.

Do you think we can improve/add something to https://github.com/keptn-sandbox/datadog-service#development? Or have a different CONTRIBUTING.md altogether? If yes, what are the benefits to do so?