This change has many improvements:
- We don't use `LockRefPtr` to hold instances of many base devices as
with the DeviceManagement class. Instead, we have a saner pattern of
holding them in a `NonnullRefPtr<T> const`, in a small-text footprint
class definition in the `Device.cpp` file.
- The awkwardness of using `::the()` each time we need to get references
to mostly-static objects (like the Event queue) in runtime is now gone
in the migration to using the `Device` class.
- Acquiring a device feel more obvious because we use now the Device
class for this method. The method name is improved as well.
This device is a block device that allows a user to effectively treat an
Inode as a block device.
The static construction method is given an OpenFileDescription reference
but validates that:
- The description has a valid custody (so it's not some arbitrary file).
Failing this requirement will yield EINVAL.
- The description custody points to an Inode which is a regular file, as
we only support (seekable) regular files. Failing this requirement
will yield ENOTSUP.
LoopDevice can be used to mount a regular file on the filesystem like
other supported types of (physical) block devices.
