PLT-6471 Properly panic when translations can't be loaded (#6414)

* PLT-6471 Properly panic when translations can't be loaded

* Print usage messages when errors occur during CLI initialization

* Reverted behaviour of FindDir and added second return value to it

* Fixed merge conflict

api/file_test.go

@@ -805,7 +805,7 @@ func TestGetInfoForFilename(t *testing.T) {
 }
 
 func readTestFile(name string) ([]byte, error) {
-	path := utils.FindDir("tests")
+	path, _ := utils.FindDir("tests")
 	file, err := os.Open(path + "/" + name)
 	if err != nil {
 		return nil, err

api/user_test.go

@@ -747,7 +747,7 @@ func TestUserUploadProfileImage(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		path := utils.FindDir("tests")
+		path, _ := utils.FindDir("tests")
 		file, err := os.Open(path + "/test.png")
 		if err != nil {
 			t.Fatal(err)