Webhook Configuration

[AugustMiller]

I encountered an error when saving users prior to configuring the plugin:

1. Install plugin;
2. Create/save/register a user;
3. Observe error;

This catches errors thrown by the Stripe API and only queues the sync job when it can be reached.

Additionally, it…

• …cleans up the Webhook settings screen messaging, and switches to a UserException so that the error is surfaced when running with devMode off (see “Breaking Changes,” below);
• …narrows the scope of CSRF changes in the webhooks controller to preserve them for other CP requests;
• …adjusts some Prettier settings so GitHub stops complaining;

Breaking Changes?

I swapped out the yii\base\InvalidConfigException for yii\web\ServerErrorHttpException so that the error message would be surfaced to the user (as a subclass of yii\base\UserException) when devMode is off.

If another extension were to try and catch this somewhere (?), their functionality might break if they weren't using a more relaxed parent class like yii\base\Exception.

[i-just]

Thanks August! All looks good.

Both this and PR#9 probably warrant a new minor release (not patch).