Properly model startup and shutdown cost

[BDonnot]

Is your feature request related to a problem? Please describe.

Today, the data are fed to grid2op, but they are not really used. To do that, we would need a "state" for each generator: on / off

Describe the solution you'd like

This could be used to simulate a market dispatch for example.

Describe alternatives you've considered

For now it is not possible to do it.

Additional context

[BDonnot]

This requires other attributes such as "is_gen_connected" and things like that.

This might be better done when introducing load shedding in the version 2.0