Use SQLDatabaseToolkit for Agent sql Skill

[tmichaeldb]

Description

This PR updates agents to use Langchain's SQLDatabaseToolkit. We used to use this, but for some reason, we migrated to only using a single skill to query a database, rather than multiple useful skills in a toolkit.

Type of change

• ⚡ New feature (non-breaking change which adds functionality)

Verification Process

To ensure the changes are working as expected:

• Test Location: Specify the URL or path for testing.
• Verification Steps: Create & use an agent locally with the Python SDK & sql skill

Additional Media:

• I have attached a brief loom video or screenshots showcasing the new functionality or change.

Checklist:

• My code follows the style guidelines(PEP 8) of MindsDB.
• I have appropriately commented on my code, especially in complex areas.
• Necessary documentation updates are either made or tracked in issues.
• Relevant unit and integration tests are updated or added.

[dusvyat]

see question above, otherwise looks good