Fully-static EntityInfoHandler

[ajkyffin]

In order to remove synchronized blocks, the PrivateEntityInfo instances are created during class static initialization and stored in immutable objects, making the class fully thread-safe.

Since everything is available in static variables, there is no need to instantiate the class, so all the methods are made static.

[patrick-austin]

Only found one thing, should work fine as is but wanted to check whether we can remove the (potentially redundant) HashSet, or not.

[patrick-austin]

Thanks for the explanation.