Always enable Newton3 within one cell

[FG-TUM]

Is your feature request related to a problem? Please describe.
When calculating the forces within one cell (or any other quantity) should always be doable with Newton3.
However, when mixing functor calls with Newton3 == false in a Newton3 == true iteration the total energy is off by a factor of 0.5.
This is because of the following:
When calculating the global values, if Newton3 is activated, all values are divided by two:

AutoPas/src/autopas/molecularDynamics/LJFunctor.h

Lines 173 to 176 in 0255376

	if (newton3) {
	upot *= 0.5;
	virial = utils::ArrayMath::mulScalar(virial, (double)0.5);
	}

and later if newton 3 is deactivated again:

AutoPas/src/autopas/molecularDynamics/LJFunctor.h

Lines 749 to 754 in 0255376

	if (not newton3) {
	// if the newton3 optimization is disabled we have added every energy contribution twice, so we divide by 2
	// here.
	_upotSum *= 0.5;
	_virialSum = utils::ArrayMath::mulScalar(_virialSum, 0.5);
	}

Describe the solution you'd like
For deciding whether or not to divide everything by 0.5 do not (ab)use the Newton3 flag but introduce another.

Describe alternatives you've considered
🤷‍♂️

Additional context
At the moment we call the functor twice with Newton3 == false.