chore(ci): add separate github action workflow that runs eslint

[SamMousa]

The current azure pipelines are very hard to read for developers not familiar with them. Also they are very slow and do a lot.

This PR adds an extra workflow for PRs that just runs eslint via github actions. Note: since this is an open source repo the CI minutes for this are free afaik.

[SamMousa]

Just check this ESLint speed xD 58 seconds!!