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/cmd/oohelperd/internal/internal.go

@@ -1,61 +0,0 @@
-package internal
-
-import (
-	"encoding/json"
-	"fmt"
-	"io"
-	"io/ioutil"
-	"net/http"
-
-	"github.com/ooni/probe-cli/v3/internal/engine/netx"
-	"github.com/ooni/probe-cli/v3/internal/engine/version"
-)
-
-// Handler implements the Web Connectivity test helper HTTP API.
-type Handler struct {
-	Client            *http.Client
-	Dialer            netx.Dialer
-	MaxAcceptableBody int64
-	Resolver          netx.Resolver
-}
-
-func (h Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	w.Header().Add("Server", fmt.Sprintf(
-		"oohelperd/%s ooniprobe-engine/%s", version.Version, version.Version,
-	))
-	if req.Method != "POST" {
-		w.WriteHeader(400)
-		return
-	}
-	if req.Header.Get("content-type") != "application/json" {
-		w.WriteHeader(400)
-		return
-	}
-	reader := &io.LimitedReader{R: req.Body, N: h.MaxAcceptableBody}
-	data, err := ioutil.ReadAll(reader)
-	if err != nil {
-		w.WriteHeader(400)
-		return
-	}
-	var creq CtrlRequest
-	if err := json.Unmarshal(data, &creq); err != nil {
-		w.WriteHeader(400)
-		return
-	}
-	measureConfig := MeasureConfig{
-		Client:            h.Client,
-		Dialer:            h.Dialer,
-		MaxAcceptableBody: h.MaxAcceptableBody,
-		Resolver:          h.Resolver,
-	}
-	cresp, err := Measure(req.Context(), measureConfig, &creq)
-	if err != nil {
-		w.WriteHeader(400)
-		return
-	}
-	// We assume that the following call cannot fail because it's a
-	// clearly serializable data structure.
-	data, _ = json.Marshal(cresp)
-	w.Header().Add("Content-Type", "application/json")
-	w.Write(data)
-}