Add support for logging suppliers in Logged classes

[shueja]

This adds the supplier as equivalent to

@Log
public <type> key() {
   return supplier.getAs<Type>();
}

but with no reflection necessary.

[oh-yes-0-fps]

Is there any reason Struct Suppliers aren't supported, is it an issue with java generics?

[shueja]

Closing this PR, half-baked effort made outdated by major refactors. Also this feature needs to get the value of the supplier every loop, instead of just logging it directly.