Add unfolded versions of the legacy (v3) exception-handling tests

[keithw]

The conclusion in #1653 & #1661 looks to be to support the legacy exception-handling instructions except for parsing their folded form in the text format. The proposal's tests use the folded form, so they can't be run directly.

This PR adds unfolded versions of the current legacy exception-handling tests (except for 7 assert_malformed directives that are commented out because of #1671).

(Context: I've been working on adding folding support to wasmprinter by annotating the for_each_operator macro with the category or arity of each instruction, with an automated test that the annotation matches the validator's behavior. So it would be helpful to have better test coverage of these instructions given that they'll be supported by the validator.)

[alexcrichton]

Thanks for this!

Also I think that as the motivation grows to add support for the legacy exceptions proposal I think it's worthwhile to reconsider re-adding the folded forms to the text parser if that would make testing and/or other constructs easier.