HDAWG does not verify prefetch requirements #928
Description
The HDAWG unfortunately does not seem to verify the prefetch requirements for the CT-based playback as of zhinst 25.07.
Irrespective of this, even if it was verified and produced errors, this means one has to resort to tricks described in the manual for programs that exceed the 256kSa/1024-blocks cache, e.g. potentially inserting playzero() commands (I do not know yet if this will work). In brief evaluation of the situation, it seems easiest to introduce an explicit "ZeroPT" for this issue as a small wrapper around ConstantPT, to signal the AWG that a playzero can safely be inserted.
The reason to use this explicitly is that with playzero no registers are initiliazed, which otherwise might be a purpose of a zero-valued ConstantPT, thus they have to be translated differently.