Add file system specific remove() methods (#670171)

This commit only adds a remove() method to every file system and an
optional call to it in the relevant operations.  All remove() methods
are no operations and not enabled.

The remove() method provides explicit controlled removal of a file
system before the partition is deleted or overwritten by being formatted
or pasted into.  When implemented, it appears as an extra step in the
relevant operation.  The file system specific remove() method is
explicitly allowed to fail and stop the operations currently being
applied.

This is different to the existing erase_filesystem_signatures() which
wipes any previous file system signatures immediately before a new file
system is written to ensure there is no possibility of the partition
containing two or more different file system signatures.  It never fails
or reports anything to the user.

NOTE:
Most file systems should NOT implement a remove() method as it will
prevent recovery from accidental partition deletion.

Bug #670171 - Add LVM PV read-write support