Support Gemini's URL context, Claude's Web fetch

[Pfaufisch]

Both Google and Anthropic recently added the possibility to include URLs in messages and have the content from these URLs retrieved. This eliminates the need to use tools such as Firecrawl.

For the Gemini API this is called URL context, with Claude it's called Web fetch.

Would be great if LibreChat supported these tools by adding according parameter(s).