Proposal: incorporate superpmicollect functionality into jitutils

The "superpmicollect" tool is both a coreclr unit test for testing SuperPMI, and a generalized SuperPMI collection harness.

Consider incorporating the superpmicollect functionality into jitutils and using it for creating a tool to easily create SuperPMI collections.

Current superpmicollect source: https://github.com/dotnet/runtime/blob/master/src/coreclr/tests/src/JIT/superpmi/superpmicollect.cs

This would somewhat duplicate the functionality in the superpmi.py script (https://github.com/dotnet/runtime/blob/master/src/coreclr/scripts/superpmi.py). However, they might be advantages in simplicity to adding it to the same suite of tools already used by the JIT, implemented in C#.