feature: added support for dot env files

[KannappanChida]

Hi @d-biehl

I've raised PR# for the below enhancement , can you please review and guide me if any further changes needed.

https://github.com/d-biehl/robotcode/issues/163

I'm new to this repo, can you please let me whether any doc related with build and contribution are available.

https://github.com/robotframework/robotframework/blob/master/BUILD.rst https://github.com/robotframework/robotframework/blob/master/CONTRIBUTING.rst

[d-biehl]

Sorry for the late reply, I'm a bit busy at the moment and now RoboCon is coming up. I will do a review after RoboCon.