add viewer/windows files

ios/Classes/PolyvoxFilamentPlugin.m

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+#import "PolyvoxFilamentPlugin.h"
+#if __has_include(<polyvox_filament/polyvox_filament-Swift.h>)
+#import <polyvox_filament/polyvox_filament-Swift.h>
+#else
+// Support project import fallback if the generated compatibility header
+// is not copied when this plugin is created as a library.
+// https://forums.swift.org/t/swift-static-libraries-dont-copy-generated-objective-c-header/19816
+#import "polyvox_filament-Swift.h"
+#endif
+
+@implementation PolyvoxFilamentPlugin
++ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
+  [SwiftPolyvoxFilamentPlugin registerWithRegistrar:registrar];
+}
+@end