Enhancing dotenv function

[rrmistry]

Enhancing the dotenv function with few enhancements:

• Handling environment variable names and values with quotes (' or ")
• Handling comments in ".env" variable file
• Gracefully moving on if ".env" file name not found
• Printing line, file name, and line number for invalid formatted lines in ".env" files

This should resolve https://github.com/tilt-dev/tilt-extensions/issues/444

[atta]

Hi a nice thing to add would be: to also remove the \r on the end of each line if it exist for better windows support

[rrmistry]

Hi a nice thing to add would be: to also remove the \r on the end of each line if it exist for better windows support

The current PR relies on the StarLark function strip.

Looking at the documentation, it seems that when called without any parameters then it removes all whitespace. But it is not explicitly clear if it is \n or \r or both.

A simple task could be to add an explicit test case for this to make sure future breaking changes are caught (if any) for \r character support.

I can update this PR as soon as I get a chance. Thanks for pointing this out @atta !