refactor(mlablocate*): move from i/e/internal to internal (#385)

We've been flattening the package structure for some time now.

While there, add very basic examples.

internal/mlablocatev2/fake_test.go

@@ -0,0 +1,46 @@
+package mlablocatev2
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/ooni/probe-cli/v3/internal/iox"
+)
+
+type FakeTransport struct {
+	Err  error
+	Func func(*http.Request) (*http.Response, error)
+	Resp *http.Response
+}
+
+func (txp FakeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	time.Sleep(10 * time.Microsecond)
+	if txp.Func != nil {
+		return txp.Func(req)
+	}
+	if req.Body != nil {
+		iox.ReadAllContext(req.Context(), req.Body)
+		req.Body.Close()
+	}
+	if txp.Err != nil {
+		return nil, txp.Err
+	}
+	txp.Resp.Request = req // non thread safe but it doesn't matter
+	return txp.Resp, nil
+}
+
+func (txp FakeTransport) CloseIdleConnections() {}
+
+type FakeBody struct {
+	Data []byte
+	Err  error
+}
+
+func (fb FakeBody) Read(p []byte) (int, error) {
+	time.Sleep(10 * time.Microsecond)
+	return copy(p, fb.Data), fb.Err // simplifed but OK
+}
+
+func (fb FakeBody) Close() error {
+	return nil
+}