MM-35518 - Add CodeQL check

[srkgupta]

Summary

Added step to run automated CodeQL checks. Once this file is merged, the codeql checks (code scanning checks) will automatically be performed on following conditions:

• new pull requests to master branch
• scheduled to run every week once (it automatically pulls the latest codeql checks added, if any)

Ticket Link

Fixes https://mattermost.atlassian.net/browse/MM-35518

[hanzei]

The starter-template contains boiler plate code for community members to pick up. I'm hesitant to include this CI pipeline into it as it has nothing to do with plugins specifically.

Is there an urgent need to check the code of this repo despite it's template nature?

[srkgupta]

Hi @hanzei
Thanks for checking. I initially added the codeql here thinking this might be a base against which other plugin repos would have been created. However upon looking into the code, I found there's nothing much here other than just boilerplate code. So we can skip this one. I will go ahead and close this. Thanks.