refactor(oohelperd): better distinguish different helpers (#434)

Part of https://github.com/ooni/probe/issues/1733

internal/cmd/oohelperd/internal/tcpconnect.go

@@ -1,42 +0,0 @@
-package internal
-
-import (
-	"context"
-	"sync"
-
-	"github.com/ooni/probe-cli/v3/internal/engine/experiment/webconnectivity"
-	"github.com/ooni/probe-cli/v3/internal/engine/netx"
-)
-
-// CtrlTCPResult is the result of the TCP check performed by the test helper.
-type CtrlTCPResult = webconnectivity.ControlTCPConnectResult
-
-// TCPResultPair contains the endpoint and the corresponding result.
-type TCPResultPair struct {
-	Endpoint string
-	Result   CtrlTCPResult
-}
-
-// TCPConfig configures the TCP connect check.
-type TCPConfig struct {
-	Dialer   netx.Dialer
-	Endpoint string
-	Out      chan TCPResultPair
-	Wg       *sync.WaitGroup
-}
-
-// TCPDo performs the TCP check.
-func TCPDo(ctx context.Context, config *TCPConfig) {
-	defer config.Wg.Done()
-	conn, err := config.Dialer.DialContext(ctx, "tcp", config.Endpoint)
-	if conn != nil {
-		conn.Close()
-	}
-	config.Out <- TCPResultPair{
-		Endpoint: config.Endpoint,
-		Result: CtrlTCPResult{
-			Failure: newfailure(err),
-			Status:  err == nil,
-		},
-	}
-}