Introducing resource limits on Windows

[Maelkum]

This PR introduces resource limits on Windows. These are not request-specific limits, but cumulative limits for all Blockless Runtime executions.

Implementation

Resource limits are set using Job Objects.

Since Go syscall documentation is scarce, here is MSDN documentation for relevant syscalls:

• CreateJobObject
• AssignProcessToJobObject
• QueryInformationJobObject

Testing

To test this manually, I used this code to spin up a number of processes, and the hcsshim jobobject-util tool to query resource limits for the job object; also tweaked it locally to print out pids of the assigned processes.

Also tested with a full-fledged executor.

For Go test code, I spun up another process doing a sleep* and created resource limits for it.

* - because Windows doesn't have sleep by default and timeout.exe cannot be used in scripts, I used a variant with a ping to localhost to simulate sleep