Io.async / io.concurrent lacks per-call context argument, making priority scheduling difficult to express with `std.Io`

Recently I started dabbling with zig and in particular with the std.Io. Comming from the rust async world, where I use non mainstream async runtimes such as monoio or glommio (glommio will be subject of this topic in particular), I found the interface in it’s current shape to be biased towards certain implementations. One of the inspirations for glommio was a C++ framework seastar, which uses scheduling groups. Each of the group has a configurable number of shares in order to proportionally div...