Ensure LayoutVersion is unique and monotonicaly increasing in LayoutFeature enums

Currently OMLayoutFeature and HDDSLayoutFeature has a field to store the LayoutVersion associated with the Feature itself.
We do not ensure in any way to have that version increasing strictly monotonically, and that would be a desirable property, as the abstract version manager uses the version as a key in a map, and if there is a collision, then that can cascade features having the same version.

The best way would possibly be to use the ordinal of the enum, but there might be other solutions for this.