Golang x/tools/internal/mcp: Add ability to provide a custom http.Client when creating mcp.NewSSEClientTransport

The SSE implementation of the MCP client currently hard codes http.DefaultClient https://github.com/golang/tools/blob/439ea2f0f815f46421aaecd85ffd0f75b0a303f9/internal/mcp/sse.go#L336

It should be possible to provide your own http.Client if customization of the client is needed.

Comment From: andrey-star

I can create a PR as follows:

func NewSSEClientTransport(baseURL string) *SSEClientTransport {
    return NewSSEClientTransportWithHTTPClient(baseURL, http.DefaultClient)
}

func NewSSEClientTransportWithHTTPClient(baseURL string, httpClient *http.Client) *SSEClientTransport {
    url, err := url.Parse(baseURL)
    if err != nil {
        panic(fmt.Sprintf("invalid base url: %v", err))
    }
    return &SSEClientTransport{
        sseEndpoint: url,
        httpClient:  httpClient,
    }
}

Comment From: gopherbot

Change https://go.dev/cl/681115 mentions this issue: internal/mcp: add the ability to provide a custom HTTP client for SSE client connections