Follow Drupal.attachBehaviors() example to attach vsite_register.js once #4194

#4194 

### For reviewer

* All functional changes are in [this commit](https://github.com/openscholar/openscholar/commit/e54af019ce7c4cfdf56aa9867844903bd9b3dd96)
* There's alot of formatting changes that don't impact behavior

#### Changes

* Removed unnecessary initialization condition
* Use context param and move all `$.bind()` behaviors inside of a `$.once()` callback