Resume with only one tag

[ahuoguo]

• fix wrong assumption on locals of main fucntion in evalTop
• preliminary implementation for wasmfx with a single tag

TODO:

• The wizard test suite seems to use a lot of ref.null. It seems a nice next step to start supporting ref.null seriously
• I make a ContV type also have a Handler type. I feel like I did not use mkont at all in the implementation for suspend, cont.new, resume but I think mixing mkont and handlers mess things up
• Implement mutable global variables for cont-bind3.wast defined here