[Feature request] Moar GC counters!

It would be nice if we added:

gc-heap-size-committed - Today we show the number of allocated bytes, but the GC commits more than it allocates, sometimes substantially so. This would help identify where that memory is being used.
gc-heap-size-committed-peak - This would show the most memory the GC memory ever committed in the process. It would help evaluate memory limits
gc-survival-rate-gen0/1/2 - Help understand the rate at which short lived objects are being promoted into higher generations