There was only one permanent storage location for these: as a member
in the Mount class.
That member is never modified after Mount initialization, so we don't
need to worry about races there.
Since the ProcFS doesn't hold many global objects within it, the need
for a fully-structured design of backing components and a registry like
with the SysFS is no longer true.
To acommodate this, let's remove all backing store and components of the
ProcFS, so now it resembles what we had in the early days of ProcFS in
the project - a mostly-static filesystem, with very small amount of
kmalloc allocations needed.
We still use the inode index mechanism to understand the role of each
inode, but this is done in a much "static"ier way than before.
This is done by merging all scattered pieces of derived classes from the
ProcFSInode class into that one class, so we don't use inheritance but
rather simplistic checks to determine the proper code for each ProcFS
inode with its specific characteristics.
