Add `.icon` (icon composer) icon support

[JoshBashed]

Closes #118

Copilot generated summary:

This pull request adds support for using .icon files (layered icon format) as app icons on Apple platforms, in addition to the existing support for .png and .icns files. It introduces a new LayeredIconCreator utility for converting .icon files to .icns, updates the resource bundling logic to handle these new icon types, and improves the documentation to reflect the expanded icon format support.

Support for new icon formats:

• Added support for using .icon files as app icons on Apple platforms, alongside .png and .icns files, by updating the compileAppIcon method in DarwinBundler to handle .icon files and call the new LayeredIconCreator utility. [1] [2] [3]
• Introduced the LayeredIconCreator utility for converting .icon files to .icns using actool, along with a dedicated error type for handling related errors. [1] [2]

Resource bundling and asset catalog improvements:

• Updated ResourceBundler to compile asset catalogs and .icon files together when present, refactored parameters to use the full BundlerContext, and improved handling of temporary files and resource copying. [1] [2] [3] [4] [5] [6]
• Added logic to determine the correct target device names for actool based on the Apple platform, ensuring proper icon generation for all supported targets.

Documentation updates:

• Updated the documentation to describe the new supported icon formats and provide guidance on when to use each format. [1] [2]