refactor: move more commands to internal/cmd (#207)

* refactor: move more commands to internal/cmd

Part of https://github.com/ooni/probe/issues/1335.

We would like all commands to be at the same level of engine
rather than inside engine (now that we can do it).

* fix: update .gitignore

* refactor: also move jafar outside engine

* We should be good now?

internal/engine/internal/httpx/fake_test.go

@@ -1,44 +0,0 @@
-package httpx
-
-import (
-	"io/ioutil"
-	"net/http"
-	"time"
-)
-
-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 {
-		ioutil.ReadAll(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 {
-	Err error
-}
-
-func (fb FakeBody) Read(p []byte) (int, error) {
-	time.Sleep(10 * time.Microsecond)
-	return 0, fb.Err
-}
-
-func (fb FakeBody) Close() error {
-	return nil
-}