Support component graph configs with m:n battery-inverter connections

[shsms]

What's needed?

Currently multiple parts of the SDK expect that each battery is connected to a single inverter. This needs to be generalized, such that there can be configs like

• multiple inverters connected to a single battery
• multiple batteries connected to a single inverter
• multiple batteries connected to multiple inverters

Proposed solution

This needs to be implemented and/or tested in these modules:

• PowerDistributor should support m:n battery-inverter connections #663
• BatteryPool should support m:n battery-inverter connections
• More updates for n:m support - battery pool's power formula #730
• PowerDistributingActor's BatteryStatusTracker needs to be updated
• Test against the sandbox

Notes

Taken from the discussion below:
We can always assume that all inverters are equal, e.g. it doesn't matter in which part of the microgrid they release power.
The currently discussed and preferred solution is to stack inverters to max. efficiency (lower power -> lower efficiency)