Refactor to avoid the implicit compile when executing setup.py

* **Bindings:** Move the creation of the ``FFI`` instance to the class creation, while moving the loading of the library to class instantiation. This allows the ``setup.py`` to import the class, but not instantiate it so that implicit compile doesn't get triggered.
* **Padding/Constant Time:** Create a ``LazyLibrary`` class which will wrap a ``FFI`` instance and will dispatch attribute access to an underlying loaded library which will be loaded on the first attribute access. This allows the ``setup.py`` to import the module, but not load the library so that implicit compile doesn't get triggered.
* ~~Monkeypatch the ``Verifier`` instance to disable the automatic & implicit compilation that can occur automatically.~~
Oof, flake8 isn't happy with this. It should be all one section `binascii`, `sys`, `threading`.