This fixes a few event listener memory leaks in the debug view:

• Registers the InputBox as disposable to templateDisposables
• Tracks elementDisposables and templateDisposables separately to clear element event listeners when an element is disposed and template event listeners when the template is disposed
• Changed the IDisposable Array to a DisposableStore (not really necessary but it seemed easier to work with a DisposableStore)

Before

The number of event listeners when debugging a javascript file 17 times grows from 3220 to 9936:

After

The number of event listeners when debugging a javascript file 17 times grows from 2499 to 3731:

The number leaking event listeners seems to be ~80% less in this case. Nevertheless, it seems likely that are still additional memory leaks since the number of event listeners is still growing.