[TIMOB-28558] TiAPI: Add property "imageIsMask" to Ti.UI.Button

*Summary:* We should add a new boolean "imageIsMask" property to Ti.UI.Button. When set true, the "image" assigned to the button will be tinted based on the "tintColor" or the default theme color. When set false, the "image" will be displayed as-is. *Current Behavior:* On iOS, the button's "image" is always masked. On Android, the button's "image" is always displayed as-is and is never masked. This feature allows for parity between Android and iOS. *Note:* We may want to make a breaking-change on Android to have it default to masking the "image" by default like iOS. This would also match Google's material design. Especially since the Java MaterialButton masks its icon by default and Titanium is not currently leveraging this feature. *Example:*

const window = Ti.UI.createWindow({ layout: "vertical" });
window.add(Ti.UI.createButton({
	title: " imageIsMask true",
	image: OS_IOS ? "controls.png" : "controls@3x.png",
	imageIsMask: true,
	top: 80,
}));
window.add(Ti.UI.createButton({
	title: " imageIsMask true (Green)",
	image: OS_IOS ? "controls.png" : "controls@3x.png",
	imageIsMask: true,
	tintColor: "green",
	top: 20,
}));
window.add(Ti.UI.createButton({
	title: " imageIsMask false",
	image: "RedLogo.png",
	imageIsMask: false,
	top: 20,
}));
window.open();

!Button-Android-Light.png|thumbnail! !Button-Android-Dark.png|thumbnail! !Button-iOS-Light.png|thumbnail!