Avoids creating a private field for each input driver

[BDisp]

Fixes

• Fixes #_____

Proposed Changes/Todos

• Todo 1

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• I've named my PR in the form of "Fixes #issue. Terse description."
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• My code follows the Terminal.Gui library design guidelines
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[BDisp]

Closing this. So many conflicts.

[tig]

This is great! Thank you.

In gui-cs#4376 I'm in the middle of removing a bunch of legacy cruft that resulted in some pretty significant renaming and refactoring of all this stuff. I'm going to finish what I'm working on right now before merging this; its highly likely that i'll have to port what you did here vs. merge it though.