SEP-1036: Add support for URL Mode Elicitation for secure out-of-band interactions

The MCP Core Maintainers have approved this feature and it will presumably be included in the next version of the MCP spec.

https://github.com/modelcontextprotocol/modelcontextprotocol/pull/887