Add dist env detection via env vars

[gkroiz]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

Fixes #91

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in GitHub issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[gkroiz]

@tchaton here is the PR based on our conversations in #91. I realized that there are several other objects that used _DistributedEnv, so decided not to go down the route of passing _DistributedEnv as an optional argument. Instead, I went with adding environment variables that can override the detected vars.

Two things regarding this PR's precheck.

1. I couldn't find a Contributor guideline file, is this signifcantly different than the lightning contributer guideline file?
2. I didn't find a lot of documentation worth updating, but if you know of any documentation relevant here, I would be happy to update.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (main@dc29634). Click here to learn what that means.

Additional details and impacted files

@@          Coverage Diff          @@
##             main    #95   +/-   ##
=====================================
  Coverage        ?    77%           
=====================================
  Files           ?     30           
  Lines           ?   3982           
  Branches        ?      0           
=====================================
  Hits            ?   3050           
  Misses          ?    932           
  Partials        ?      0