Add debug visualizer for dynamic methods

[stephentoub]

It can be difficult when using dynamic methods to understand exactly what IL was generated, which is important when debugging them. We should consider adding a simple IL debug visualizer on DynamicMethod.

[eerhardt]

cc @drewnoakes - from https://github.com/drewnoakes/il-visualizer

[jkotas]

We have visualizer like this for crossgen2:

https://github.com/dotnet/runtime/blob/master/src/coreclr/src/tools/Common/TypeSystem/IL/MethodILDebugView.cs
https://github.com/dotnet/runtime/blob/master/src/coreclr/src/tools/Common/TypeSystem/IL/ILDisassembler.cs

[stephentoub]

Great. We can always improve it further, but just using / minimally-adapting that would be a great min bar.

[krwq]

cc: @steveharter

[danmoseley]

Marking up for grabs, as this is a nice self contained project - albeit probably significant work - that we could use eg for debugging the regex engine.

@jkotas would it need any runtime work?

[danmoseley]

This would presumably be a significant project -- @eiriktsarpalis maybe we need a label for that? I guess we have 'hard problem' but it's not quite right.