SQLalchemy Refactor - PostgreSQL support, `CREATE TEMP TABLE` logic, Guidance LlamaCpp Model class

[parkervg]

This PR attempts to make the underlying SQL adapter logic DBMS-agnostic, so that we can operate over most SQL-style databases, and not just SQLite.

Specifically, the Database class in ./blendsql/db/_database.py now uses sqlalchemy rather than sqlite3.

Additionally, the underlying 'temporary session table' logic was rewritten, so that we no longer manage cleaning-up of our temp tables within the Python level. Instead (and much more cleanly), we initialize all tables via CREATE TEMP TABLE commands, which work in both SQLite and PostgreSQL.

Other notable commits:

• 2283526 - Added LlamaCpp integration
• f963eff, 3c38b3c, 5fd465b, a0bdb37, a457ddf, ce19992 - updating lark _peg_grammar
  • This will actually get used in a later PR
• 670d00e - rename blendsql.py to blend.py
• c027388 - adding PostgreSQL class
• 85418e2 - No longer handling temp session table logic ourselves, instead relying on CREATE TEMP TABLE syntax