Add CombineKeyboard Library

[Woollim]

I'd like to add CombineKeyboard library over to the Combine community. this library was made inspired by RxKeyboard in RxSwift coomunity.

• replace copyright with "Copyright (c) Combine Community" in code
• replace copyright in README
• replace copyright in LICENSE
• Add cocoapods@combine.community as an owner of your project's CocoaPod by using pod trunk add-owner YourPodName cocoapods@combine.community.
• update CI badge (this library don't have any CI)
• update CI settings (this library don't have any CI)
• update the remote URL of the Podspec (if any)
• transfer repository ownership (once you're a contributor)
• fork the repo back to your personal account