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_importedstruct_test.go

@@ -0,0 +1,95 @@
+package binding_test
+
+import "github.com/wailsapp/wails/v2/internal/binding/binding_test/binding_test_import"
+
+type ImportedStruct struct {
+	AWrapperContainer binding_test_import.AWrapper `json:"AWrapperContainer"`
+}
+
+func (s ImportedStruct) Get() ImportedStruct {
+	return s
+}
+
+var ImportedStructTest = BindingTest{
+	name: "ImportedStruct",
+	structs: []interface{}{
+		&ImportedStruct{},
+	},
+	exemptions:  nil,
+	shouldError: false,
+	want: `
+export namespace binding_test {
+	export class ImportedStruct {
+		AWrapperContainer: binding_test_import.AWrapper;
+		static createFrom(source: any = {}) {
+			return new ImportedStruct(source);
+		}
+		constructor(source: any = {}) {
+			if ('string' === typeof source) source = JSON.parse(source);
+			this.AWrapperContainer = this.convertValues(source["AWrapperContainer"], binding_test_import.AWrapper);
+		}
+		convertValues(a: any, classs: any, asMap: boolean = false): any {
+			if (!a) {
+				return a;
+			}
+
+			if (a.slice) {
+				return (a as any[]).map(elem => this.convertValues(elem, classs));
+			} else if ("object" === typeof a) {
+				if (asMap) {
+					for (const key of Object.keys(a)) {
+						a[key] = new classs(a[key]);
+					}
+					return a;
+				}
+				return new classs(a);
+			}
+			return a;
+		}
+	}
+}
+
+export namespace binding_test_import {
+	export class AWrapper {
+		AWrapper: binding_test_nestedimport.A;
+		static createFrom(source: any = {}) {
+			return new AWrapper(source);
+		}
+		constructor(source: any = {}) {
+			if ('string' === typeof source) source = JSON.parse(source);
+			this.AWrapper = this.convertValues(source["AWrapper"], binding_test_nestedimport.A);
+		}
+		convertValues(a: any, classs: any, asMap: boolean = false): any {
+			if (!a) {
+				return a;
+			}
+			if (a.slice) {
+				return (a as any[]).map(elem => this.convertValues(elem, classs));
+			} else if ("object" === typeof a) {
+				if (asMap) {
+					for (const key of Object.keys(a)) {
+						a[key] = new classs(a[key]);
+					}
+					return a;
+				}
+				return new classs(a);
+			}
+			return a;
+		}
+	}
+}
+
+export namespace binding_test_nestedimport {
+	export class A {
+		A: string;
+		static createFrom(source: any = {}) {
+			return new A(source);
+		}
+		constructor(source: any = {}) {
+			if ('string' === typeof source) source = JSON.parse(source);
+			this.A = source["A"];
+		}
+	}
+}
+`,
+}