[Multi-User]: Part 0 - Add support for logging in with Google

[sabaimran]

Incoming

• Integrate the Django ORM for interacting with the db and managing tables
• Allows users to login / sign up with their Google account
• This currently has no impact whatsoever on functionality, it just introduces the baseline support so we can later partition settings by user in the DB and later support pg_vector for embeddings storage

Begins implementation for https://github.com/khoj-ai/khoj/pull/487. As a follow-up to this, the next step will be to integrate this into the actual application and partition user settings and data storage by user.

[gitguardian[bot]]

⚠️ GitGuardian has uncovered 2 secrets following the scan of your pull request.

Please consider investigating the findings and remediating the incidents. Failure to do so may lead to compromising the associated services or software components.

🔎 Detected hardcoded secrets in your pull request

| GitGuardian id | Secret | Commit | Filename | | | -------------- | ------------------------- | ---------------- | --------------- | -------------------- | | [8175313](https://dashboard.gitguardian.com/incidents/8175313?occurrence=115308712) | Django Secret Key | 869c37f4aac0963529fef8650c12feaa6edb9727 | src/app/settings.py | [View secret](https://github.com/khoj-ai/khoj/commit/869c37f4aac0963529fef8650c12feaa6edb9727#diff-131c5c27cd822962a341b4700640cbecac31937b15c46b1df90c569c918f09e3R24) | | [8175313](https://dashboard.gitguardian.com/incidents/8175313?occurrence=116432382) | Django Secret Key | 6fa925e898e431d5ace1cf1780960f655dc433f3 | src/app/settings.py | [View secret](https://github.com/khoj-ai/khoj/commit/6fa925e898e431d5ace1cf1780960f655dc433f3#diff-131c5c27cd822962a341b4700640cbecac31937b15c46b1df90c569c918f09e3L24) |

🛠 Guidelines to remediate hardcoded secrets

1. Understand the implications of revoking this secret by investigating where it is used in your code. 2. Replace and store your secrets safely. [Learn here](https://blog.gitguardian.com/secrets-api-management?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) the best practices. 3. Revoke and [rotate these secrets](https://docs.gitguardian.com/secrets-detection/detectors/specifics/secret_key_in_django_config#revoke-the-secret?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment). 4. If possible, [rewrite git history](https://blog.gitguardian.com/rewriting-git-history-cheatsheet?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment). Rewriting git history is not a trivial act. You might completely break other contributing developers' workflow and you risk accidentally deleting legitimate data. To avoid such incidents in the future consider - following these [best practices](https://blog.gitguardian.com/secrets-api-management/?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) for managing and storing secrets including API keys and other credentials - install [secret detection on pre-commit](https://docs.gitguardian.com/ggshield-docs/integrations/git-hooks/pre-commit?utm_source=product&utm_medium=GitHub_checks&utm_campaign=check_run_comment) to catch secret before it leaves your machine and ease remediation.

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