IDE-1646 adding disable custom jsps validation rule for liferay-hook.xml...

I have found a better API that I think we should use for looking up the validator and checking the rules.  Lets use this one instead:

https://github.com/gamerson/eclipse-wtp-webresources/blob/185edd066e7a9fc7623ee3195984fe4c19f12945/org.eclipse.a.wst.html.webresources.core/src/org/eclipse/wst/html/webresources/core/validation/WebResourcesValidator.java#L202-203

ValManager.getDefault().getValidator( "id", project )