Add support for pgvector

[dhruv-anand-aintech]

Follow the guidelines at https://github.com/AI-Northstar-Tech/vector-io#adding-a-new-vector-database to implement support for PGVector in Vector-io

Join the Discord server for the library at https://discord.gg/RZbXha62Fg, and ask any questions on the #vector-io-dev channel.

Checklist of features for completion

• Add mapping of distance metric names
• Support local and cloud instances
• Automatically create Python classes for index being exported
• Export
  • Get all indexes by default
  • Option to Specify index names to export
  • DB-specific command line options (make_parser)
  • Allow input on terminal for each option above (via input() in python) export_vdb
  • Handle multiple vectors per row
• Import
  • DB-specific command line options (make_parser)
  • Handle multiple vectors per row
  • Allow input on terminal for each option above (via input() in python) export_vdb

PGVector python client documentation: https://github.com/pgvector/pgvector-python

For any questions, contact @dhruv-anand-aintech on Linkedin (https://www.linkedin.com/in/dhruv-anand-ainorthstartech/)