Divide F64 capacity but keep F64 benefits

Possibility to split an F64 capacity into smaller sub-capacities, while retaining F64 benefits (e.g. Power BI free readers can read content).

The capacity admin should be able to set a "ceiling" on how much compute each sub-capacity is allowed to use. This will help to avoid compute consumption getting out of hand.

The sum of the max limits ("ceilings") for each sub-capacity could exceed the max limit of the original capacity. So we could be "optimistic" when assigning limits to sub-capacities, if we choose.

However, if the actual combined consumption of the sub-capacities hits the limits of the original capacity, then we would of course be throttled just like today.

The purpose would be the ability to limit the resource consumption of some workspaces, by assigning them to a limited sub-capacity, while also keeping the benefits of being on an F64+ capacity.