ability to disable heap dump on OOM

[vanhtuan0409]

Mill launcher always adds +HeapDumpOnOutOfMemoryError parameter. It should be optional with a flag to toggle on / off

ref: https://github.com/com-lihaoyi/mill/blob/main/runner/launcher/src/mill/launcher/MillProcessLauncher.java#L241

[lihaoyi]

Thanks for the report. Is there a particular reason you may want it turned off? It seems like heap dumps are a useful thing to have when things OOM, and if things don't OOM then it doesn't matter anyway

[vanhtuan0409]

We run our CI in github actions with limited ephemeral storage. Heap dump actually consume all disk space. So it actually no use for us anyway