Refactor KeyFilter

[melloware]

###Defect Fixes @mertsincan this uses event.key which is much more browser standard than the old event.which etc and is much more reliable.

It also allows us to remove all the special Safari and Opera and Mozilla handling this class was doing.

Here is a great Keyboard event viewer: https://w3c.github.io/uievents/tools/key-event-viewer.html

Also its universally supported now: https://caniuse.com/?search=event.key

Its a start of refactoring for #2101

[melloware]

Also it looks like this code originated from PrimeNG so it was proabbly valid a long time ago with these IE and Opera etc fixes none of which should be necessary now.

[mertsincan]

@melloware can you create a Github issue?

[melloware]

Yep

[melloware]

Done!