[WIP] Experiments with worker threads#550

Draft

FelixMcFelix wants to merge 6 commits intomasterfrom

Commits on Jun 4, 2024

First attempt at thread creation/management.
FelixMcFelix
committed

Commits on Jun 10, 2024

Mailbox types.
FelixMcFelix
committed

Commits on Jun 12, 2024

A (very slow/contended) worker thread
FelixMcFelix
committed

Commits on Jun 13, 2024

Commits on Jun 14, 2024

Fixup kbench, stick thread into poll for 'fun'
FelixMcFelix
committed