fix: Updated index_file() to use x2text adapter

[chandrasekharan-zipstack]

What

• Updated index_file() to use x2text adapter
• Added util for getting the file MIME type
• Minor fix on exceptions.py
• Bumped version to 0.11.0 - since it introduces some minor breaking changes

Why

• Text extraction during indexing had to be done with the new x2text adapter
• Adding util for file MIME type will help other tools determine the file type easily

How

• Text extraction is performed by using the x2text adapter

Relevant Docs

Related Issues or PRs

Dependencies Versions / Env Variables

Notes on Testing

• Added the SDK as a local file dependency to the backend and was able to create an index. However executing prompts wasn't explicitly checked

Screenshots

Checklist

I have read and understood the Contribution Guidelines.