Fix binding generation special cases (#1902)

* Make binding.go easier to test

* Fix non-deterministic namespace order for bindings

* Add binding tests

* Fix nested import structs, non-string map keys, and escape invalid variable names

Co-authored-by: Lea Anthony <lea.anthony@gmail.com>

v2/internal/binding/binding_test/binding_nonstringmapkey_test.go

@@ -0,0 +1,32 @@
+package binding_test
+
+type NonStringMapKey struct {
+	NumberMap map[uint]any `json:"numberMap"`
+}
+
+func (s NonStringMapKey) Get() NonStringMapKey {
+	return s
+}
+
+var NonStringMapKeyTest = BindingTest{
+	name: "NonStringMapKey",
+	structs: []interface{}{
+		&NonStringMapKey{},
+	},
+	exemptions:  nil,
+	shouldError: false,
+	want: `
+export namespace binding_test {
+	export class NonStringMapKey {
+		numberMap: {[key: number]: any};
+		static createFrom(source: any = {}) {
+			return new NonStringMapKey(source);
+		}
+		constructor(source: any = {}) {
+			if ('string' === typeof source) source = JSON.parse(source);
+			this.numberMap = source["numberMap"];
+		}
+	}
+}
+`,
+}