improve class.implements()

[brettmc]

Actually, you can find the interface through this method: https://docs.rs/phper/latest/phper/classes/struct.ClassEntry.html#method.from_globals

I think we can modify the prototype of implements, something like:

fn implements(&mut self, interface: Interface)  

Then we can think about how to design it better later.

Originally posted by @jmjoy in #187 (comment)

[jmjoy]

Solved by #189