[feat] Generate a d.ts file for @tauri-apps/api/core:invoke

[alex-way]

Describe the problem

There isn't any type safety for the invoke function, so it's extremely easy to pass invalid arguments.

Describe the solution you'd like

I think it would be great if rust could generate a d.ts file with the different registered handlers.

This should be possible by creating a d.ts file in the root of the "frontend" src like so:

declare module "@tauri-apps/api/core" {
	export function invoke<T>(
		cmd: "greet",
		args: {name: string},
		options?: unknown,
	): Promise<T>;

    export function invoke<T>(
		cmd: "meet",
		args: {greeting: string},
		options?: unknown,
	): Promise<T>;

// Optionally exclude this to provide stricter type safety
    export function invoke<T>(
		cmd: string,
		args?: unknown,
		options?: unknown,
	): Promise<T>;
}

There may be a better way to provide type safety but this was just my initial thoughts.

Alternatives considered

No response

Additional context

No response

[FabianLars]

Duplicate of #1514, thanks for the feature request.