Enable MPS on Mac always

Seems it isn't limited to usefulness on Apple Silicon.
See #118
We can't verify this, but it does improve things substantially when running the Intel build on Apple Silicon (still required for CZI files, for example) - so is beneficial anyway.

src/main/java/qupath/ext/instanseg/core/PytorchManager.java

@@ -50,7 +50,7 @@ public static Collection<String> getAvailableDevices() {
                 availableDevices.add(name);
             }
             // If we could use MPS, but don't have it already, add it
-            if (GeneralTools.isMac() && "aarch64".equals(System.getProperty("os.arch"))) {
+            if (GeneralTools.isMac()) {
                 availableDevices.add("mps");
             }
             // CPU should always be available