This patch uses the last changes in the SDL3 clipboard to have that clean separation
between mime type announcement and retrieving the corresponding clipboard data. With
these changes we don't have anymore that spurious notifications where we loose the
clipboard ownership, and also we don't trigger data retrieval by calling functions
like SDL_ClipboardHasText().
This patch adds a success flag on clipboard data requests, so that we can react
correctly in the SDL handler. I've also made some errors non fatal like if you requests
a kind of data that doesn't exist the client should not terminateit's for that.
