Refactor: Updated api schema and removed redundant types

[Saranya-jena]

Proposed changes

• Updated mongo audit field schema in project and user collection to store username, userID, email .
• Updated members structure in mongo schema to store username, name and email.
• Updated JSON schema in all the auth resources to follow camel case convention.
• Removed redundant data types for projects.
• Refactored code in project related API to reduce number of DB calls.
• Added new API end point to fetch users based on their invitation state in a project.

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Types of changes

What types of changes does your code introduce to Litmus? Put an x in the boxes that apply

• New feature (non-breaking change which adds functionality)
• Bugfix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices applies)

Checklist

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• I have read the CONTRIBUTING doc
• I have signed the commit for DCO to be passed.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

Dependency

• Please add the links to the dependent PR need to be merged before this (if any).

Special notes for your reviewer:

[SarthakJain26]

error can be handled here