Remove MergeAndRebaseHelper's dependency on RefsHelper

We want to make MergeAndRebaseHelper a dependency of RefsHelper instead.

pkg/gui/controllers/helpers/merge_and_rebase_helper.go

@@ -17,17 +17,14 @@ import (
 )
 
 type MergeAndRebaseHelper struct {
-	c          *HelperCommon
-	refsHelper *RefsHelper
+	c *HelperCommon
 }
 
 func NewMergeAndRebaseHelper(
 	c *HelperCommon,
-	refsHelper *RefsHelper,
 ) *MergeAndRebaseHelper {
 	return &MergeAndRebaseHelper{
-		c:          c,
-		refsHelper: refsHelper,
+		c: c,
 	}
 }