This patch:
- refactors `NetworkManager`/`FrameManager` so that they enable all the
relevant domains themselves. This is a preparation for OOPIF support and
migration onto fetch domain.
- moves `networkManager` ownership into `FrameManager`. This way it's clear who owns what.
- stops enabling Security domain: it saves quite some traffic over
websocket since it no longer sends annoying "SecurityStateChanged" events.
Instead, use `Security.setIgnoreCertificateErrors` method.
- consolidates network cache state in network manager. This even fixes a
bug with caching and request interception interop.
