Add typings for explicit resource management

This is a follow-up to #23818.

When targeting any existing ES version, TypeScript transpiles `using ...` and doesn't require any typings.

However, when targeting ESNext, it expects `using ...` to be a native feature, and then looks up `[Symbol.dispose]` in the type and fails with a type validation error if it doesn't exist.

Since there's no way to do conditional compilation based on target version in TS, I'm adding this property to type declarations but marking with `ts-ignore` so that `Symbol.dispose` not existing is not an error in versions below ESNext.

Author: RReverser

src/lib/libembind_gen.js

@@ -418,6 +418,8 @@ var LibraryEmbind = {
           '  delete(): void;\n',
           '  deleteLater(): this;\n',
           '  isDeleted(): boolean;\n',
+          '  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.\n',
+          '  [Symbol.dispose](): void;\n',
           '  clone(): this;\n',
           '}\n',
         );

test/other/embind_tsgen.d.ts

@@ -9,6 +9,8 @@ export interface ClassHandle {
   delete(): void;
   deleteLater(): this;
   isDeleted(): boolean;
+  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.
+  [Symbol.dispose](): void;
   clone(): this;
 }
 export interface Test extends ClassHandle {

test/other/embind_tsgen_ignore_1.d.ts

@@ -20,6 +20,8 @@ export interface ClassHandle {
   delete(): void;
   deleteLater(): this;
   isDeleted(): boolean;
+  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.
+  [Symbol.dispose](): void;
   clone(): this;
 }
 export interface Test extends ClassHandle {

test/other/embind_tsgen_ignore_2.d.ts

@@ -8,6 +8,8 @@ export interface ClassHandle {
   delete(): void;
   deleteLater(): this;
   isDeleted(): boolean;
+  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.
+  [Symbol.dispose](): void;
   clone(): this;
 }
 export interface Test extends ClassHandle {

test/other/embind_tsgen_ignore_3.d.ts

@@ -9,6 +9,8 @@ export interface ClassHandle {
   delete(): void;
   deleteLater(): this;
   isDeleted(): boolean;
+  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.
+  [Symbol.dispose](): void;
   clone(): this;
 }
 export interface Test extends ClassHandle {

test/other/embind_tsgen_module.d.ts

@@ -9,6 +9,8 @@ export interface ClassHandle {
   delete(): void;
   deleteLater(): this;
   isDeleted(): boolean;
+  // @ts-ignore - If targeting lower than ESNext, this symbol might not exist.
+  [Symbol.dispose](): void;
   clone(): this;
 }
 export interface Test extends ClassHandle {