Test bad WASMs

[jayz22]

What

Parts of #1145

• [x] corrupt metadata custom section
• [x] floating point instructions
• [ ] SIMD instructions,
• [ ] other post-MVP extensions
  • [x] multi-value
• [x] very large import table that imports the same host functions over and over
• [x] importing nonexistent host functions
• [x] multiple memories
• [x] exporting nonexistent functions
• [ ] invalid table entries
  • [x] FuncRef
  • [ ] ExternRef
• [x] start functions (these are banned)
• [ ] invalid const-expressions and active table references in elements table
• [ ] invalid const-expressions in active data segment mode
• [x] multiple data-count sections, sections with an invalid count
• [ ] very large versions of every section type:
  • [x] Custom (not valid)
  • [ ] Type
  • [x] Import
  • [x] Function
  • [ ] Table
  • [x] Memory
  • [x] Global
  • [x] Export
  • [x] Start (not valid)
  • [x] Element
  • [x] Code
  • [x] Data
  • [x] DataCount

[graydon]

@jayz22 this is great work, thanks!