feat(android): add letterSpacing to Label

[m1ga]

iOS can do letterspacing with a attributedString already. Android doesn't have this property. As it just a text property I've added it the same way as lineSpacing so it is a native Label property.

var win = Ti.UI.createWindow({
	layout: "vertical"
});
var textLabel = Ti.UI.createLabel({
	text: "some text",
	letterSpacing: -0.1,
	font: {
		fontSize: 40
	}
});
var textLabel2 = Ti.UI.createLabel({
	text: "some text",
	letterSpacing: 0.1,
	font: {
		fontSize: 40
	}
});

win.add([textLabel, textLabel2]);
win.open();

[Copilot]

Pull Request Overview

This PR adds support for the letterSpacing property on Android Labels, mirroring the implementation of lineSpacing.

• Updates the API documentation to include letterSpacing.
• Adds a constant for letterSpacing in TiC.java.
• Implements letterSpacing handling in TiUILabel both during initial property processing and on property changes.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
apidoc/Titanium/UI/Label.yml	Documents the new letterSpacing property
android/titanium/src/java/org/appcelerator/titanium/TiC.java	Introduces the PROPERTY_LETTER_SPACING constant
android/modules/ui/src/java/ti/modules/titanium/ui/widget/TiUILabel.java	Adds letterSpacing logic in property processing and change handling