[Multi-User Part 1]: Enable storage of settings for plaintext files based on user account

[sabaimran]

Incoming

• Partition configuration for indexing local data based on user accounts
• Store indexed data in an underlying postgres db using the pgvector extension
• Add migrations for all relevant user data and embeddings generation. Very little performance optimization has been done for the lookup time
• Apply filters using SQL queries
• Start removing many server-level configuration settings
• Configure GitHub test actions to run during any PR. Update the test action to run in a containerized environment with a DB.
• Update the Docker image and docker-compose.yml to work with the new application design

Closes #466, Closes #345

Closes #195. On my local analysis, memory consumption in my machine on the prior setup with my local org notes was around 10-12 GB of RAM. With the pg_vector integration, it's around 2-3 GB.

[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) |

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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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