Legacy Exception Handling

[GerardSmit]

This PR implements https://github.com/WebAssembly/exception-handling. The following is done:

Module structure

• [x] Tags
  • [ ] Clean-up
  • [ ] Import
  • [ ] Export
  • [ ] Name section

Control flow operators

• [x] try
• [x] catch
• [x] catch_all
• [ ] delegate
• [x] throw
• [x] rethrow

Other tasks

• [x] Fix possible out of range exceptions (when the tag index is out of range).
• [ ] Resolve all TODO's in code:
  • [ ] Verify expected result type if there is no value
  • [ ] Validate for invalid tags in throw and catch
  • [ ] Validate for invalid argument types in throw

In C# I've created a WebAssemblyException which is thrown by the IL generator.
If the exception has parameters, the generic type will be used (WebAssemblyException<T0> and WebAssemblyException<T0, T1>. This is to prevent boxing.

[RyanLamansky]

As noted in #59, I don't want to merge the WebAssembly. prefixing in the OpCode XML due to that being a Rider bug. Any chance you could rebase without those changes to cut down on the size of this PR? Other than that, I'm pretty excited about what you've accomplished here.