[2.0] `classic_address` isn't typed properly

[mvadari]

It looks like property aliases aren't supported in mypy right now: https://github.com/python/mypy/issues/6700

The best solution is likely to just copy-paste the address code, with a TODO for when mypy has resolved the issue.

[JST5000]

For people encountering this issue before the next release, if you change from .classic_address to .address the issue goes away.

[ckniffen]

Closed by #617