cgroup aware `Base.Sys.cpu_info` and `Base.Sys.total_memory`

[tanmaykm]

Not sure if it is possible, but it will be good to have Base.Sys.cpu_info and Base.Sys.total_memory aware of linux cgroups and report cgroup info instead.

It will also be useful when Julia is being run within a docker container with cgroup limits.

[vtjnash]

I tried looking into this before, and tried to write down a few of my findings: #17987 (comment)

[vtjnash]

may be addressed by libuv/libuv#2249

[maleadt]

This isn't really fixed: although #36479 introduced uses of uv_get_contrained_memory for setting-up the heap and managing collections, that information isn't exposed in the Sys module as requested here. Furthermore, with Linux distributions moving to cgroup2, uv_get_contrained_memory becomes useless unless libuv/libuv#2323 is merged. So I think we better re-open this issue.