feat: add pgvector full_text_search

[jasonkang14]

Checklist:

Important

Please review the checklist below before submitting your pull request.

• Please open an issue before creating a PR or link to an existing issue
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

Description

Added Full Text Search on pg_vector according to PSQL Full Text Search. works well with different languages such as English, Korean, and Chinese

Closes #7190

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update, included: Dify Document
• Improvement, including but not limited to code refactoring, performance optimization, and UI/UX improvement
• Dependency upgrade

Testing Instructions

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Tested locally after changing the VECTOR_STORE configuration in .env to pgvector. Please refer to the screenshot below

** edited **
fixed a bug associated with having a whitespace in query

[jasonkang14]

I will look at the test code for pg_vector and see how I can fix it and push it again

done!