For Pause related functions, would be good to have a .UI_WAIT_BTN_START (and .UI_WAIT_BTN_SELECT) wait_flag

[pkoutoupis]

Is your feature request related to a problem? Please describe.
Not a bug but a problem with when I try to use a modal dialogue box as a pause menu that is tied to the press of the Start button. BUT in order to unpause, my only options are A, B or ANY (which includes D-PAD). It would be nice if I can have Start as an option.

Describe the solution you'd like
Asking for Start (and Select) button presses to be added to wait_flag, for example, like in closing modal dialogue boxes. A .UI_WAIT_BTN_START (and .UI_WAIT_BTN_SELECT) wait_flag.

Describe alternatives you've considered
I have exported the engine and added the wait_flag for the Start button in my personal project. And I forked the Advanced Dialogue plugin, added the wait_flag option in there. It seems to work as expected. Here is what I did: https://github.com/pkoutoupis/gb-studio-misc-extras

Additional context
None.