Postponed items from the code review (#1068):

1. internal operation ApproximatelyMultiplexZ:
   This cost of this can be cut in half, by applying the first part of its relative phase decomposition, which is then uncomputed in the adjoint call to the within block.
   (by Mathias)

2. internal operation ApproximatelyMultiplexPauli:
   This can be made more concise with Microsoft.Quantum.Intrinsic.MapPauli. Note that currently MapPauli is internal.
   (by Mathias)
   (Resolved)