Legacy Exception Handling

[GerardSmit]

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

Module structure

• Tags
  • Clean-up
  • Import
  • Export
  • Name section

Control flow operators

• try
• catch
• catch_all
• delegate
• throw
• rethrow

Other tasks

• 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.