Create packages for easy installation

Hi, it's a nice library. However, it seems that it's not currently available as the package for Swift Package Manager or via CocoaPods, so that the library could be easily integrated with the application target. Supporting both would serve multiple purposes:

• Makes it easier to integrate with the applications
• Keeps the library code separate from the app code
• Makes it very easy to upgrade to new versions of BlurHash
• Assists discovery

I recommend creating a library definition files (.podspec and package.swift), so that the library could be integrated with the dependency management tools.