Fix: Support more than 256 stations/waypoints/roadstops per class. (#10793)

It was already possible to define more than 256 per class, but not possible
to use them as the index used in GUI and passed through commands was limited
to a byte.

Codechange: Let the compile generate the master command table out of templated command traits.

This is using a non-intrusive type-traits like templated system, which
allows compile-time validation that the command table and the command
enum match up.