Add SearXNG to supported search engines

[odellus]

Is your feature request related to a problem? Please describe.
I run SearXNG locally because it is free

Describe the solution you'd like
Accept PR #677 that adds the SearXNG tool

Is this not possible with the current options.
No it's not possible. I had to write it myself.

Describe alternatives you've considered
Just using my own branch seems suboptimal

Additional context
Pretty please

[tisDDM]

Just in case:
I am running a private Searxng-Instance behind a basic auth as well. So I very quickly implemented a MCP Server for using it as a tool. I created a Github-Repo as well, think it should work out of the box for everyone.

searxng-mcp