Add pgvector provider implementation

[pankajkoti]

This PR is part of our larger effort to add first-class integrations to support LLMOps that was presented at Airflow Summit.

This PR adds explicitly the pgvector Provider.
https://github.com/pgvector/pgvector

Email Discussion related to the effort can be found here - https://lists.apache.org/thread/0d669fmy4hn29h5c0wj0ottdskd77ktp

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[pankajastro]

@utkarsharma2 we have security.rst in other provider docs. example: https://github.com/apache/airflow/blob/main/docs/apache-airflow-providers-apache-cassandra/security.rst do we need to add this here too?

[potiuk]

@utkarsharma2 we have security.rst in other provider docs. example: https://github.com/apache/airflow/blob/main/docs/apache-airflow-providers-apache-cassandra/security.rst do we need to add this here too?

Yes. This file is generated automatically when publishing documentation (because soon we will start generating SBOM information there automatically), but it's good to add it.

[potiuk]

(we will improve that part when we automate SBOM publishing).

[pankajastro]

please rebase this see #34921 (comment)

[Lee-W]

Overall, it looks great :)

Left a few minor suggestions

1. missing type annotation
2. using f-string instead of string concatenation

[kaxil]

Hmm wait! Some of Build CI images step errored/failed, how did other tests succeed!

@pankajkoti You might need to keep close eyes on the running tests in main. And revert or quick fix things if they fail

[potiuk]

This was unrelated though (bullseye -> bookworm) and fixed here: #35503

[potiuk]

It should not impact overal "health" of the PR.