[mono] Don't use direct wrapper when invoking cctors, so all cctors can share one wrapper

[kg]

Should improve interp startup time a bit, since right now we generate one wrapper for every cctor, and lots of cctors get called during app startup. From my testing this doesn't break AOT, but I can't tell whether this is accidentally causing us to interpret cctors that were AOT'd.

I added some new assertions in various places because of some crashes I hit while making my way to this change; happy to take them out.

cc @BrzVlad @kotlarmilos would appreciate thoughts on the right way to do this. this is just my first attempt that worked, i still don't understand all this code well

my thinking here:

• the calli family of opcodes expect a function pointer, but it may not be possible to have a function pointer for all cctors (i.e. wasm where you can't jit arbitrary function pointers at runtime, at least not yet). and making a fn ptr for them is wasteful since we call them exactly once. so i added calli_monomethod, which expects a monomethod. interp_runtime_invoke is passing a monomethod to the wrapper, so this makes it compatible when it wasn't before.
• only enabled for cctors right now to reduce the blast radius. From my testing cctors are the main semi-hot path where we rely on runtime invoke.
• should interp_runtime_invoke actually be passing monomethod? it seems like that only works because direct wrappers ignore the method pointer, i can't figure out why it's passing one. (obviously, the new calli_monomethod uses it)
• the new calli_monomethod has assertions to ensure we're only using it for the expected scenario
• we previously assumed that the call target would always be native for a runtime_invoke wrapper, which isn't true at least in the wasm interp scenario since we can't jit a function pointer for it. so i added a check that sets native=0 if jit call isn't supported for the target. i'm guessing i got this wrong and it will need to change for jit and aot to work correctly.

[kg]

Surprisingly, this passes tests. So it just needs expert review I think, especially to make sure it's not going to regress AOT startup by knocking cctors into the interp or perhaps demoting AOT'd wrappers to interpreted ones.

[BrzVlad]

This approach looks fragile and confusing to me. I think we should just have a different wrapper for runtime invoke that we know can only be called from interpreter (and that should never be jit/aot compiled). It could completely reuse the code for the already existing runtime invoke wrappers.

I think we should be able to pass pretty much just the InterpMethod* as argument. Seems quite dubious that with each unique interp ldftn we would attempt to aot-lookup the method. I think this should be more lazy, but it needs some thinking.

[kg]

This approach looks fragile and confusing to me. I think we should just have a different wrapper for runtime invoke that we know can only be called from interpreter (and that should never be jit/aot compiled). It could completely reuse the code for the already existing runtime invoke wrappers.

Should I add a new wrapper type or a new wrapper subtype? I think changing the generated code for the wrapper shouldn't be too hard.

I think we should be able to pass pretty much just the InterpMethod* as argument. Seems quite dubious that with each unique interp ldftn we would attempt to aot-lookup the method. I think this should be more lazy, but it needs some thinking.

OK, so it needs to be calli_interpmethod, not calli_monomethod? I can do that.