Provide access to interceptor bindings from InvocationContext

[Ladicek]

I plan to add tests for this to the CDI TCK. It is expected that EJB is not affected by this by any means.

[Ladicek]

Thank you! FYI, I looked at the changes again and realized there's an inconsistency between the javadocs of getInterceptorBinding(Class) and getInterceptorBindings(Class), so I pushed a fix.

[arjantijms]

@Ladicek thanks!