(CFACT-124) Refactor block device resolver.

Refactoring the block device resolver into a base type responsible for
adding the facts and child types that are responsible for collecting
data.

This also adds the "disks" structured fact representing disk data.
(CFACT-124) Refactor SSH resolver into base type.

Refactoring the SSH resolver into a base type responsible for adding
facts and child types that are responsible for collecting SSH key data.

This also adds the ssh structured fact.
(CFACT-124, CFACT-76) Refactor networking resolver.

Refactor the networking resolver into a base type that is responsible
for adding a fact and child types that are responsible for collecting
data.  This keeps the fact definition in one place and allows Windows to
share the base implementation.

This commit also adds a structured "networking" fact that collects all
networking data into one place.