`windows-implement` macro for Rust enums

Nobody has claimed this yet.

### Suggestion

I am writing a Rust SDK for PowerToys Command Palette, and it has an interface like below:

```
enum CommandResultKind {
Dismiss, // Reset the palette to the main page and dismiss
GoHome, // Go back to the main page, but keep it open
GoBack, // Go back one level
Hide, // Keep this page open, but hide the palette.
KeepOpen, // Do nothing.
GoToPage, // Go to another page. GoToPageArgs will tell you where.
ShowToast, // Display a transient message to the user
Confirm, // Display a confirmation dialog
};
[uuid("f9d6423b-bd5e-44bb-a204-2f5c77a72396")]
[contract(Microsoft.CommandPalette.Extensions.ExtensionsContract, 1)]
interface ICommandResultArgs{};
[contract(Microsoft.CommandPalette.Extensions.ExtensionsContract, 1)]
interface IGoToPageArgs requires ICommandResultArgs{
String PageId { get; };
NavigationMode NavigationMode { get; };
}
[contract(Microsoft.CommandPalette.Extensions.ExtensionsContract, 1)]
interface IToastArgs requires ICommandResultArgs{
String Message { get; };
ICommandResult Result { get; };
}
[contract(Microsoft.CommandPalette.Extensions.ExtensionsContract, 1)]
interface IConfirmationArgs requires ICommandResultArgs{
String Title { get; };
String Description { get; };
ICommand PrimaryCommand { get; };
Boolean IsPrimaryCommandCritical { get; };
}
[contract(Microsoft.CommandPalette.Extensions.ExtensionsContract, 1)]
interface ICommandResult {
CommandResultKind Kind { get; };
ICommandResultArgs Args { get; };
}
```

Currently, I write

```rust
#[implement(ICommandResult)]
pub struct CommandResult {
}
```

Then manually copy everything macro generated and change definition to:

```rust
// #[implement(ICommandResult)]
pub enum CommandResult {
Dismiss,
GoHome,
GoBack,
Hide,
#[default]
KeepOpen,
GoToPage(ComObject),
ShowToast(ComObject),
Confirm(ComObject),
}
```

It would be helpful if I can use `#[implement(ICommandResult)]` directly.

Start by examining the existing #[implement(ICommandResult)] behavior and compare it with the manually generated enum implementation shown in the issue. Done means the attribute can be applied directly to a Rust enum and generates the required ICommandResult implementation, including variant-specific argument types.

Written by the indexing model from the issue text.