Reenable beep on touch for buttons (but not empty space)

[Funkenjaeger]

This reenables the beep functionality. It uses pygame, as with Kivy's SoundLoader I could not seem to eliminate a noticeable lag between button press and the sound playing.

This also switches away from using "on_touch_down" on the HomePage as a catch-all that caused it to beep when you touch anywhere at all, including empty spaces. Instead the beep function is associated with each button (etc.), so it only beeps when you tap something actually interactive.

[Funkenjaeger]

Note that this requires some system changes outside of the RCP repo to get sound working (at least with my raspberry pi 5 and the wisecoco touchscreen display you sell). Namely, create /root/.asoundrc with the following contents:

pcm.!default {
    type plug
    slave.pcm "plughw:0,0"
}

ctl.!default {
    type hw
    card 0
}

You might instead be able to edit /etc/asound.conf and change the default cards from 1 to 0 there.
I suppose these types of changes might need to flow back to your ospi repo instead.