Migrate FindEdges too imagej-ops

To begin the migration of net.imagej.plugins.commands, FindEdges and its
associated helper classes have been migrated to imagej-ops. This
migration will allow for all imagej ops to be found in one place once
completed.
Migrate ImageCalculator to imagej-ops
WIP migrate commands.io package

All contents from net.imagej.plugins.commands.io have been migrated.
However, there seems to be several redundant imports. Before these are
deleted, it would be prudent to revise the code and ensure that their
deletion would not break something vital