Toaster Android 2.3.1

What's Changed

• Encapsulate default toaster creation by @5AbhishekSaxena in #18
• Clean up by @5AbhishekSaxena in #19
• Update README.md by @5AbhishekSaxena in #21
• Refactor Toaster ktx API functions as top-level functions. by @5AbhishekSaxena in #23

Full Changelog: 2.3.0...2.3.1