[FEAT]: Add connector for LangChain PgVector?

[NisugaJ]

What would you like to see?

I would like to manage my Langchain PgVector ( langchain-postgres ) vector store collections using VectorAdmin.

Context

• The collection names are saved inside langchain_pg_collection.
• The embeddings are saved inside langchain_pg_embedding.

Proposal

For connecting the database, I would like to provide the
db_host, db_name, db_username, db_password.

After the connection is successful, I would like to select the collection_name which I want to manage/sync.