New evaluators

We have added some more evaluators, a new string matching and a Levenshtein distance evaluation.

Improvements

• Updated documentation for human evaluation
• Made improvements to Human evaluation card view
• Added dialog to indicate testset being saved in UI

Bug fixes

• Fixed issue with viewing the full output value during evaluation
• Enhanced error boundary logic to unblock user interface
• Improved logic to save and retrieve multiple LLM provider keys
• Fixed Modal instances to support dark mode

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