Automatically Remove White Space at end of key

[stpaultim]

Was just experimenting with the Key module (1.x-3.4.1) and Open AI module and was getting some frustrating errors. It turns out the problem was that when copying and pasting the key into the textarea field, I brought along unnecessary white space. Once this white space was removed, the problem was resolved.

This could be avoided by automatically removing white spaces at the end of a key.

Or at least, providing some help text to remind users that white text at end of a key MAY cause problems and that they should check for it.