This change renames the `opendc-simulator-resources` module into the
`opendc-simulator-flow` module to indicate that the core simulation
model of OpenDC is based around modelling and simulating flows.

Previously, the distinction between resource consumer and provider, and
input and output caused some confusion. By switching to a flow-based
model, this distinction is now clear (as in, the water flows from source
to consumer/sink).

This change removes the ability to transform the duration of a pull from
the SimResourceForwarder class. This ability is not used anymore, since
pushes are now done using a method instead of a command.

This change removes the distributor and aggregator interfaces in favour
of a single switch interface. Since the switch interface is as powerful
as both the distributor and aggregator, we don't need the latter two.

This change hides the SimResourceState from public API since it is not
actively used outside of the `SimResourceContextImpl` class.

This change removes the `onUpdate` callback from the
`SimResourceProviderLogic` interface. Instead, users should now update
counters using either `onConsume` or `onConverge`.

This change updates the SimResourceContextImpl to lazily push changes to
the resource context instead of applying them directly. The change is
picked up after the resource is updated again.

This change updates the simulator implementation to always invoke the
`SimResourceConsumer.onNext` callback when the resource context is
invalidated. This allows users to update the resource counter or do some
other work if the context has changed.

This change simplifies the implementation of the
SimResourceAggregatorMaxMin class by utilizing the new push method.
This approach should offer better performance than the previous version,
since we can directly push changes to the source.

This change removes unnecessary allocations in the SimResourceInterpreter
caused by the way timers were allocated for the resource context.