FLOSS API hooks

[mr-tz]

FLOSS hooks comparably few APIs. We should:

• identify the most relevant APIs for our use case
• come up with an easy way to implement / extend these

Also we should see if we can reuse what other emulation projects are already doing.

[williballenthin]

speakeasy has a pretty good set here: https://github.com/fireeye/speakeasy/tree/master/speakeasy/winenv/api/usermode
but unfortunately many of them use internal speakeasy routines, so we can't just blindly copy-pasta. but maybe convert over the most useful?