refactor(embed.py, models.py), docs(Readme.md): Improve code readability and update documentation

[jxnl]

	:rocket: This PR description was created by Ellipsis for commit 7229348cab37799c034d5a135cd738cc5a53975c.

Summary:

This PR refactors the embed.py and models.py files in the finetune-quora-embeddings application for better readability and maintainability, and updates the Readme.md file to improve the formatting of the benchmarking results table.

Key points:

• Introduced a new Provider enum in models.py to replace the model_types literal.
• Refactored embed.py to use the new Provider enum.
• Updated embed.py to improve code readability and maintainability.

• Modified the Readme.md file to improve the formatting of the benchmarking results table.

  Generated with :heart: by ellipsis.dev

[jxnl]

wait @ivanleomk this code does not run i dont think