[FEAT] Make contributors life easier

[Nadav-Barak]

Some stuff that require fixing:

1. Split the make tests command into 3 (per data type) so contributors can work on a single sub package
2. pip install . throws error "The version specified ('dev') is an invalid version, this may not work as expected with newer versions of setuptools, pip, and PyPI. Please see PEP 440 for more details." But I ran python setup.py install and it worked.
3. Make a automated way when creating a 'good first issue' automatically will add a first comment containing relevant text with link to https://github.com/deepchecks/deepchecks/blob/main/CONTRIBUTING.rst
   Suggestion: add an additional default (similar to 'Bug' and 'Feature')
4. Add link to community slack so contributors can easily communicate with us.

Future - Bot to notify us in slack about contributors commenting out of org.

[hjain5164]

Thank you @Nadav-Barak for creating this issue and pointing out the challenges faced while setting up the project for a contributor. If you want, I can also contribute to making the fixes, better documentation for setting up the project locally, or any other aspect which would improve the developer experience.