Drops support for the WebAssembly text format (#614)

This drops the text format (%.wat) and renames
InstantiateModuleFromCode to InstantiateModuleFromBinary as it is no
longer ambiguous.

We decided to stop supporting the text format as it isn't typically used
in production, yet costs a lot of work to develop. Given the resources
available and the increased work added with WebAssembly 2.0 and soon
WASI 2, we can't afford to spend the time on it.

The old parser is used only internally and will eventually be moved to
its own repository named watzero, possibly towards archival.

See #59

Signed-off-by: Adrian Cole <adrian@tetrate.io>

examples/basic/add.go

@@ -12,6 +12,11 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
+// addWasm was generated by the following:
+//	cd testdata; wat2wasm --debug-names add.wat
+//go:embed testdata/add.wasm
+var addWasm []byte
+
 // main implements a basic function in both Go and WebAssembly.
 func main() {
 	// Choose the context to use for function calls.
@@ -22,14 +27,7 @@ func main() {
 	defer r.Close(ctx) // This closes everything this Runtime created.
 
 	// Add a module to the runtime named "wasm/math" which exports one function "add", implemented in WebAssembly.
-	wasm, err := r.InstantiateModuleFromCode(ctx, []byte(`(module $wasm/math
-    (func $add (param i32 i32) (result i32)
-        local.get 0
-        local.get 1
-        i32.add
-    )
-    (export "add" (func $add))
-)`))
+	wasm, err := r.InstantiateModuleFromBinary(ctx, addWasm)
 	if err != nil {
 		log.Panicln(err)
 	}

examples/basic/testdata/add.wat

@@ -0,0 +1,15 @@
+(module
+  ;; Define the optional module name. '$' prefixing is a part of the text format.
+  $wasm/math
+
+  ;; add returns $x+$y.
+  ;;
+  ;; Notes:
+  ;; * The stack begins empty and anything left must match the result type.
+  ;; * export allows api.Module to return this via ExportedFunction("add")
+  (func (export "add") (param $x i32) (param $y i32) (result i32)
+    local.get $x ;; stack: [$x]
+    local.get $y ;; stack: [$x, $y]
+    i32.add      ;; stack: [$x+$y]
+  )
+)