Win32: Allow user to change emulated PSP nickname, and add an OSK "bypass"

This pullrq addresses https://github.com/hrydgard/ppsspp/issues/3062, at least for Windows. Other platforms would need to add their own methods of popping a dialog box and grabbing text from the user.

In addition, I added the beginnings of a dialog box(re-using the same one from the win32 debugger) similar to JPCSP's, to let the user just use their hardware keyboard if they wish to type instead of dragging a cursor around the OSK. It'd be nice if eventually the keyboard would just directly interact with the OSK, but I'm not really sure how to do that at the moment.

There are a few caveats concering the "bypass" though:
1. It crashes the emulator if the user enters more characters than the game expects(I can't figure out how to make the textbox in the dialog box only have X characters max).
2. Russian/Japanese/non-Roman languages will simply input question marks to the game(need to use wstring I think).
3. It has a weird "delay" to it if one closes the dialog box and then tries to re-open it. After closing it, the confirm button(cross/circle) has to be pressed twice in order to bring it back up.

As a result of these snags, the OSK bypass option is Win32 only(well, until others add their versions), and is a "hidden" INI option(no UI interface to it).