[Suggestion]: acquire slot or wait at depot / station

[CactusAcolyte]

Programable signals feature a whole host of modes of slot operation, including "Acquire or wait."

Vehicle orders allow aquiring and releasing slots without using signals easily enough, and conditional order jumps have various other in slot / not in slot / attempt aquiring slot modes, with the notable absence of any comparable aquire or wait option.

In order to get a vehicle to wait at depot (or station) until a slot is available without using signals, you have to resort to having it loop on a go-to order, which looks glitchy (albeit functional) unless the depot / station order has a wait added manually on the timetable.
I think this an intended use case.

If it doesn't require a coding rebase (feel free to close the issue if it does) I think having an optional action as part of the go-to order (akin to near-end or wait until full) or a "wait in place until slot is aquired" new order type would make it feel a little bit less hacky and obscure.