fix: validate Bing service always fails

[tisfeng]

Fix #421

[tisfeng]

Since refactoring startQuery:, we don't need to call prehandleQueryTextLanguage: method manually anymore.

- (void)startQuery:(EZQueryModel *)queryModel
        completion:(void (^)(EZQueryResult *result, NSError *_Nullable error))completion {
    NSString *queryText = queryModel.queryText;
    EZLanguage from = queryModel.queryFromLanguage;
    EZLanguage to = queryModel.queryTargetLanguage;
    
    if ([self prehandleQueryTextLanguage:queryText
                                    from:from
                                      to:to
                              completion:completion]) {
        return;
    }
    
    [self translate:queryText from:from to:to completion:completion];
}

[tisfeng]

I plan to release a small fix update tonight or tomorrow.

[tisfeng]

We need to speed up the Swift refactoring and turn it from an objc project into a Swift project.

Next, in order to better add new features later, I plan to rewrite the code related to the query service (excluding the services themselves), the previous code was a bit ugly, when we refactor it later, we should try our best to optimize it, making it easier to expand.