Add ability to invoke interpreter-side PFKeys

[abrudz]

Describe the issue you are having

It can be a very powerful thing to use APL code to set up part of the development environment. The Windows IDE allows ⎕PFKEYS to automate certain tasks, and while RIDE has its own similar system, this isn't available from the APL language.

The design could e.g. be that if you set to <PF4> (which at best wouldn't make sense, or at worst would put RIDE into a loop) then RIDE seds a protocol command to the interpreter, asking it to acts as if the corresponding key was pressed. Indeed, this functionality could already be faked by sending ["Execute",{"text":"1 ⎕NQ ⎕SE'KeyPress' 'F4'","trace":0}]

4.5.4094