Safe wrappers for mimalloc Heap type?

[playXE]

mimalloc has Heap type and functions to create instance of heap and allocate from it, maybe it is worth adding wrappers for them?

[thomcc]

@playXE I never saw this and you may not care anymore, but a while ago I wrote https://gist.github.com/thomcc/e2a2ae4cc2ac470cf6f186372834d8fc but never finished it. I intend to add a implementation of AllocRef for heap under a nightly flag soonish though to get a feel for the AllocRef api.