Exported smooch init method to RN

[abrel]

This PR (ios) aims at exposing an init method directly from RN. Thus, RN users can avoid editing the AppDelegate.m file. Eventually, it is easier to maintain config for different env (CI etc...).

[wmora]

Thanks! We recently changed the signature for this method. Would you mind updating your code?

// Before
SKTSettings* settings = [SKTSettings settingsWithAppToken:@"YOUR_APP_TOKEN"];
[Smooch initWithSettings:settings];

// After
SKTSettings* settings = [SKTSettings settingsWithAppId:@"YOUR_APP_ID"];
[Smooch initWithSettings:settings completionHandler:^(NSError * _Nullable error, NSDictionary * _Nullable userInfo) {
    // Handle init result
}];