Replace unittests with pytests + update CI workflow and code doc-strings

[naik-aakash]

Closes #97, #108, #126, #144, #164 and #166

Changes

• All tests have moved out of core package into tests
• Used pytestify to convert all our unittests to pytests
• Refactor tests to use fixures mainly for testing analyze ,describe and plotting modules (results in faster test execution with minimal use of resources)
• Updated pre-commit config
• Excluded tests from coverage reports
• Updated doc building config files to exclude tests
• Add missing type hints in modules
• Update test durations file
• Fix pre-commit config file
• Include pre-commit as part of workflow
• Add tests for doc-building
• Add doc-deployment to github pages workflow (Will remove our dependency on read the docs , I am not able to check it myself as it is supposed to be run on master branch, needs to be tested)

[naik-aakash]

Hi @JaGeo, this PR is could be reviewed and merged.

[naik-aakash]

I think probably test durations file is the issue. I need to update it seems

[naik-aakash]

Hi @JaGeo , It would be best for me if you can review and merge this PR before others. I can then get started with updating the readme and other stuff 😄

[naik-aakash]

Also, workflow I used for deploying docs to gh-pages is from the following link
https://coderefinery.github.io/documentation/gh_workflow/ and a bit of atomate2 docs workflow.

So only thing we need to more is enable github pages for the Lobsterpy repo as it is stated in Step 4.

[JaGeo]

I remarked some style issues for the comments. Otherwise, it looks good.

[JaGeo]

I found a few lines that aren't covered yet by tests (cli.py). Maybe, this can be addressed as another PR.

[naik-aakash]

Hi @JaGeo , I think this PR could be merged now.

I Will resolve other minor merge conflicts that will arise in other PR when I get some time later.

[naik-aakash]

Also, please enable GitHub pages for the LobsterPy repo. Before merging this PR.