Takes functionality from NSSU2FToken/NSSU2FTokenRemote classes, and
moves it into a U2FSoftToken class. Leaves
NSSU2FToken/NSSU2FTokenRemote classes intact so as not to break U2F
API code (to be ported to async IPC in bug 1354330).
MozReview-Commit-ID: El2MCcYUrtE
Takes functionality that was in the WebAuthentication class that now
needs to be handled by the parent process, and moves it to the
U2FTokenManager singleton class. U2FTokenManager is created on the
PBackground thread during the first WebAuthn transaction, and manages
hardware access and transaction management for the lifetime of the
browser session. Patch also adds parent classes for WebAuthn IPC
protocol.
MozReview-Commit-ID: EnhgUTPdlMZ
Kyle Machulis