Remove peverify tests in favor of ILVerify

It appears that ILVerify is ready to be applied against compiler output, see my discussion with @jkotas here: https://github.com/dotnet/runtime/issues/40586.

ILVerify replaces peverify, the latter can only be used in framework assemblies and not on Core. Also, a bunch of limitations have been lifted, and it supports recent additions to the CLR. There are still a bunch of outstanding improvements, but if I understand it correctly, it can be used to verify assembly output.

It may actually be easier to integrate, perhaps it should become part of this issue: https://github.com/dotnet/fsharp/issues/9828, @vzarytovskii, what do you think?