Support for SoftMaxHeapSize?

[Holger Hoffstätte]

Hi,

I've been playing with setting SoftMaxHeapSize for ZGC in order to limit its
somewhat eager hunger for heap, and it does a really great job while still
allowing heap expansion for bursty LDS. Would this make sense for Shenandoah as
well? Compact mode does a great job already, but IMHO some conceptual feature
parity wouldn't hurt. Only if it's possible and not too much work, obviously. :)

cheers
Holger