fix: memory leak in MainThreadWorkspace

[SimonSiefke]

Fixes a memory leak in MainThreadWorkspace.

Details

When a provider is registered, it is both added to a Map called registeredEditSessionProviders as well as to this._toDispose.

this.registeredEditSessionProviders.set(handle, disposable);
this._toDispose.add(disposable);

However when a provider is unregistered, it is removed from the Map registeredEditSessionProviders, but not from this._toDispose

const disposable = this.registeredEditSessionProviders.get(handle);
disposable?.dispose();
this.registeredEditSessionProviders.delete(handle);

This causes the this._toDispose array to grow over time.

Change

The change is using a DisposableMap, ensuring this._toDispose doesn't grow when registering and unregistering providers.

private registeredCanonicalUriProviders = this._register(new DisposableMap<number, IDisposable>());

Before

When restarting extensions 37 times, the number functions in MainThreadWorkspace.$registerCanonicalUriProvider seems to grow by 3 each time. Entries 10/11:

After

When restarting extensions 37 times, the number functions in MainThreadWorkspace.$registerCanonicalUriProvider stays constant:

[Copilot]

Pull request overview

This PR aims to stop MainThreadWorkspace from accumulating undisposed provider disposables across extension restarts by switching provider registration tracking to DisposableMap and relying on the Disposable base class for lifecycle management.

Changes:

• Convert MainThreadWorkspace to extend Disposable and route disposal through super.dispose().
• Replace provider Map<number, IDisposable> fields with DisposableMap<number, IDisposable> and use deleteAndDispose(...) on unregister.

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[roblourens]

Thanks!