Add low-level overloads for all client request methods

[halter73]

If you want to manually iterate using nextCursor of a paginated response like the "tools/list" response you currently have to manually call McpClient.SendRequestAsync like so.

// ...

var toolResults = await mcpClient.SendRequestAsync<ListToolsRequestParams, ListToolsResult>(
    RequestMethods.ToolsList,
    new() { Cursor = cursor },
    McpJsonUtilities.JsonContext.Default.ListToolsRequestParams,
    McpJsonUtilities.JsonContext.Default.ListToolsResult,
    cancellationToken: cancellationToken);

// ...

cursor = toolResults.NextCursor;

// ...

Instead, it'd be nice if we offered an overload of CallToolsAsync that took the lower-level ListToolsRequestParams as a parameter and return the ListToolsResult making the nextCursor easily accessible without having to search for the right generic parameter types:

// ...

var toolResults = await mcpClient.ListToolsAsync(new() { Cursor = cursor }, cancellationToken: cancellationToken);

// ...

cursor = toolResults.NextCursor;

// ...

We'd keep the existing ListToolsAsync overload that returns an IList<McpClientTool> and doesn't take a cursor parameter, but this would enable lower-level usage without dropping down to SendRequestAsync.

I think we should add these low-level overloads that do this for every single request type defined in RequestMethods.cs. I think they already exist for server-to-client requests like SampleAsync, ElicitAsync and RequestRootsAsync, so this would make the client more consistent with the server.

[stephentoub]

Fixed by #1063