Fix Resource leak tracking issue on Windows

[ShahzaibIbrahim]

On Windows SWT, the Device implementation keeps a strong reference to Resource objects via this method:

void registerResourceWithZoomSupport(Resource resource) {
	resourcesWithZoomSupport.add(resource);
}

That means:
Every Resource with zoom support is added to the resourcesWithZoomSupport set in the Device. This is a Set<Resource>, which holds strong references. Because of this, the GC will never collect these resources, even if the application code drops all references, the Device is still referencing them.

To tackle that, we can use the WeakReference (more about it here). That will allows GC to collect the resource.

The only downside I see could be, that every time a Resource object becomes garbage collected, its corresponding WeakReference object still exists in the set, which needs to be cleared. For that, my idea is to clean up the dead references whenever win32_destroyUnusedHandles is called more specifically whenever WM_DISPLAYCHANGE or WM_DPICHANGED event happens.

Fixes: #2335

[github-actions]

Test Results

   546 files  ±0     546 suites  ±0   31m 16s ⏱️ + 2m 33s
 4 412 tests ±0   4 395 ✅ ±0   17 💤 ±0  0 ❌ ±0 
16 718 runs  ±0  16 591 ✅ ±0  127 💤 ±0  0 ❌ ±0 

Results for commit 49819b3. ± Comparison against base commit 7cf1145.

♻️ This comment has been updated with latest results.

[HeikoKlare]

The implementation looks fine and works as expected. I have only minor comments regarding code style.