Introduce keyboard shortcut for Clear buffer command

[adamsamec]

Description of the new feature/enhancement

Introduce a default keyboard shortcut, such as Control + Shift + K, for the Clear buffer command to ease keyboard users clearing the buffer.

[carlos-zamora]

Thanks for filing! This is a good idea, we don't remember why we didn't do that haha.

We're thinking about changing this action to "Clear and reset" (and adding a reset action for when someone plays around with win32 input mode).