Add Litestar framework

[0asys]

Summary of change

Adds the litestar framework as option for backend python integration.

Related issues

• https://github.com/supertokens/supertokens-python/issues/310
• https://github.com/supertokens/supertokens-python/pull/311

Test Plan

project should update the test environment to at least python3.8.

Documentation changes

Checklist for important updates

• [ ] Changelog has been updated
• [ ] coreDriverInterfaceSupported.json file has been updated (if needed)
  • Along with the associated array in supertokens_python/constants.py
• [ ] frontendDriverInterfaceSupported.json file has been updated (if needed)
• [ ] Changes to the version if needed
  • In setup.py
  • In supertokens_python/constants.py
• [ ] Had installed and ran the pre-commit hook
• [ ] Issue this PR against the latest non released version branch.
  • To know which one it is, run find the latest released tag (git tag) in the format vX.Y.Z, and then find the latest branch (git branch --all) whose X.Y is greater than the latest released tag.
  • If no such branch exists, then create one from the latest released branch.
• [ ] If have added a new web framework, update the supertokens_python/utils.py file to include that in the FRAMEWORKS variable
• [ ] If added a new recipe that has a User type with extra info, then be sure to change the User type in supertokens_python/types.py
• [ ] Make sure that syncio / asyncio functions are consistent.
• [ ] If access token structure has changed
  • Modified test in tests/sessions/test_access_token_version.py to account for any new claims that are optional or omitted by the core

Remaining TODOs for this PR

• [ ] Item1
• [ ] Item2

[rishabhpoddar]

Thanks @bpereto. Ill have a detailed look at this soon. In the meantime though, a few things are missing:

• An example app in the examples folder.
• Missing frontend integration server (in tests/frontendIntegration/ folder)