spi button debounce added

[tinyboxxx]

My friend has a noisy SPI button, which is causing unbindable buttons due to flickering. To address this, I’ve created this fix.

Currently, this feature is disabled by default and will not affect normal users.

It can be enabled using the following commands in the GUI serial:

spibtn.0.debounceen=1
spibtn.0.debouncetime=20

If this change is acceptable, I can work on integrating it into the GUI.