[Feature request] Add import from clipboard feature

[mikhirev]

As FreeOTP+ was unable to recognize a QR code (see #277), I had to do this with Camera app, then copy the recognized URI to clipboard, create a text file with text editor, paste the URI to file, save it, and only after that I was able to import it in FreeOTP+. Please provide an ability to import URI/JSON directly from clipboard.

[helloworld1]

In some later Android versions, if you select and copy the URI, it has the option to open in FreeOTP+. But yea, import from clipboard is a viable option indeed.