Add Adapter based on OpenAI and PostgreSQL pgvector extension

[alexander-schranz]

Some experimenting with OpenAI and PostgreSQL.

Reference:

• https://supabase.com/blog/openai-embeddings-postgres-vector
• https://help.openai.com/en/articles/6272952-search-transition-guide
• https://github.com/pgvector/pgvector

TODO

• Setup PostgreSQL with pgvector
• Setup PDO Connection
• Setup OpenAI Connection
• SchemaManagerTest
• IndexerTest
• Example query vector data embedding
• SearcherTest
• Save Vector Data with Document
• Search with Vector Data
• Add Filter posibility