Update support for the module linking proposal

This commit updates the various tooling used by wasmtime which has new
updates to the module linking proposal. This is done primarily to sync
with WebAssembly/module-linking#26. The main change implemented here is
that wasmtime now supports creating instances from a set of values, nott
just from instantiating a module. Additionally subtyping handling of
modules with respect to imports is now properly handled by desugaring
two-level imports to imports of instances.

A number of small refactorings are included here as well, but most of
them are in accordance with the changes to `wasmparser` and the updated
binary format for module linking.

tests/misc_testsuite/module-linking/alias.wast

@@ -7,7 +7,7 @@
   (instance $a (instantiate $m))
 
   (func (export "get") (result i32)
-    call $a.$foo)
+    call (func $a "foo"))
 )
 (assert_return (invoke "get") (i32.const 1))
 
@@ -19,7 +19,7 @@
   (instance $a (instantiate $m))
 
   (func (export "get") (result i32)
-    global.get $a.$g)
+    global.get (global $a "g"))
 )
 (assert_return (invoke "get") (i32.const 2))
 
@@ -30,7 +30,7 @@
     (data (i32.const 0) "\03\00\00\00")
   )
   (instance $a (instantiate $m))
-  (alias (instance $a) (memory $m))
+  (alias $m (memory $a "m"))
 
   (func (export "get") (result i32)
     i32.const 0
@@ -50,7 +50,7 @@
 
   (func (export "get") (result i32)
     i32.const 0
-    call_indirect $a.$t (result i32))
+    call_indirect (table $a "t") (result i32))
 )
 (assert_return (invoke "get") (i32.const 4))
 
@@ -62,11 +62,10 @@
         i32.const 5))
   )
   (instance $a (instantiate $m))
-  (instance $b (instantiate $a.$sub))
-  (alias $b.$f (instance $b) (func 0))
+  (instance $b (instantiate (module $a "module")))
 
   (func (export "get") (result i32)
-    call $b.$f)
+    call (func $b ""))
 )
 (assert_return (invoke "get") (i32.const 5))
 
@@ -79,11 +78,9 @@
     (instance $i (export "") (instantiate $sub))
   )
   (instance $a (instantiate $m))
-  (alias $a.$i (instance $a) (instance 0))
-  (alias $a.$i.$f (instance $a.$i) (func 0))
 
   (func (export "get") (result i32)
-    call $a.$i.$f)
+    call (func $a "" ""))
 )
 (assert_return (invoke "get") (i32.const 6))
 
@@ -91,48 +88,51 @@
 (module
   (type $t (func))
   (module $m
-    (func $f (type $t))
+    (func $f (type outer 0 $t))
   )
   (instance $a (instantiate $m))
 )
 
 ;; alias parent -- module
+(; TODO
 (module
   (module $a)
   (module $m
-    (instance (instantiate $a))
+    (instance (instantiate (module outer 0 $a)))
   )
   (instance (instantiate $m))
 )
+;)
 
 ;; The alias, import, type, module, and instance sections can all be interleaved
-(module
+(module $ROOT
   (module $a)
   (type $t (func))
   (module $m
     ;; alias
-    (alias $thunk parent (type $t))
+    (alias $thunk (type outer 0 $t))
     ;; import
     (import "" "" (func (type $thunk)))
     ;; module (referencing parent type)
     (module
-      (func (type $thunk))
+      (func (type outer $m $thunk))
+      (func (type outer $ROOT $t))
     )
     ;; type
     (type $thunk2 (func))
     ;; module (referencing previous alias)
     (module $m2
-      (func (export "") (type $thunk2))
+      (func (export "") (type outer $m $thunk2))
     )
     ;; instance
     (instance $i (instantiate $m2))
     ;; alias that instance
-    (alias $my_f (instance $i) (func 0))
+    (alias $my_f (func $i ""))
     ;; module
     (module $m3
       (import "" (func)))
     ;; use our aliased function to create the module
-    (instance $i2 (instantiate $m3 (func $my_f)))
+    (instance $i2 (instantiate $m3 "" (func $my_f)))
     ;; module
     (module $m4
       (import "" (func)))
@@ -141,5 +141,5 @@
   ;; instantiate the above module
   (module $smol (func $f (export "")))
   (instance $smol (instantiate $smol))
-  (instance (instantiate $m (func $smol.$f)))
+  (instance (instantiate $m "" (instance $smol)))
 )