Provide API for getting Class instances looking up in all Runtime class loaders

[vmutafov]

Currently, the Runtime uses multiple classloaders, mostly for the runtime generated classes by the Runtime Binding Generator. This might break in cases where a user requests a class with: Class.forName("com.test.SomeRuntimeGeneratedClass");

To overcome this issue, an API should be provided to lookup classes not only in the system class loader but in all class loaders used by the runtime. The API should be trivial to implement as there is already logic in the runtime to find classes in all class loaders and class caches.