feat(layer-image): add zIndex editing for layer image objects

Closes MIN-91

src/components/FunctionalArea/Modal/LayerImageObjectModal/LayerImageObjectEditFactoryModal.component.test.tsx

@@ -140,7 +140,7 @@ describe('LayerImageObjectEditFactoryModal - component', () => {
     };
     const getGlyphDataMock = jest.fn(() => glyphData);
     jest.spyOn(layerObjectFeature, 'get').mockImplementation(key => {
-      if (key === 'setGlyph') return (): void => {};
+      if (key === 'update') return (): void => {};
       if (key === 'getGlyphData') return getGlyphDataMock;
       return undefined;
     });