Exclude all numpad keys from keyboard mapping

[spoenemann]

What it does

Fixes #6872.

How to test

• Grab a Windows 10 machine and make sure at least two keyboard layouts are set up in the system preferences, so the language / keyboard selector is visible in the task bar.
• Start the Electron app, open an editor, type 3 and 9.
  • Without this fix, the cursor was moved a page down / up.
  • With this fix, the characters 3 and 9 should be written into the editor.

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[akosyakov]

@spoenemann build is failing

Grab a Windows 10

Not sure who can test it. @eclipse-theia/ecd-theia-committers ?

[thegecko]

@westbury Would you have a few minutes to give this a spin?

[westbury]

Unfortunately I cannot reproduce the problem without the fix. I have tried both the parent commit (f11045a) and also from our Electron IDE. I always see numbers for the number keys along the top row above the letters, and either numbers or page up/down etc on the numeric pad (as appropriate for num-lock on/off). I did have to connect an external keyboard to my Windows 10 laptop to get the numeric pad.

Perhaps it depends on the particular keyboard layouts? I had three already installed. If you let me know the layouts I will try with those.

[spoenemann]

I had difficulties reproducing the problem, too (see arduino/arduino-pro-ide#129). For me it helped to switch between different layouts using the task bar selector, or to remove and add again the additional layouts.

[westbury]

OK, I can now reproduce reliably by switch away from US layout and switching back. With the fix I cannot reproduce the problem at all. So I am convinced as can be that this PR fixes the problem.