Run test in github actions

[bassochette]

Changes:

Add two Github action pipelines:

• CodeQl analysis: A tool from Github to scan for security flaws
• Test: Run npm test against node 10 to 15

Both pipeline run on ubuntu-latest.
They are configured to run for every PR against master and every commits on master.

I did not remove travis config.
You can check actions on my fork https://github.com/Webeleon/image-webpack-loader/actions

close #260

[tcoopman]

Thanks, going to merge this so we can get some experience with it. Especially the code quality is something I’m not sure about. But I’m willing to check it out.

Afterwards we can maybe add a badge to the readme and remove the old pipeline