Populate ROW_KEY_PREFIX column when creating views

When a view statement is defined by the constraints articulated in PHOENIX-4555, all rows created by the view will be prefixed by a KeyRange. The view thus can simply be represented by the prefixed KeyRange generated by the expression representing the view statement.

The ROW_KEY_PREFIX column will store this KeyRange. The prefixed KeyRange will be used to create a PrefixIndex -> mapping a row prefix to a view.