Feature Request: Anti deadzones

This might be a bad name for it, although it is the name that steaminput uses. Unchanged, the analog axis is just a line intersecting the origin. Deadzone shifts the start of this line sideways. I propose this new setting which would shift the start of this line upwards as well.

This would help to mitigate the problem shown in the reWASD forum link below. I have experienced this issue to be particularly annoying when trying to use the analog sticks on the PCSX emulator.

References:

Also note that anti-deadzone will be very useful too. Basically, specifying both input and output ranges of an axis. And it should be able to be saved as a game override.

Originally posted by @keknyJi in #8502

https://forum.rewasd.com/forum/rewasd/suggestions-aa/239885-asking-if-rewasd-is-working-on-implementing-anti-deadzone-for-axial-deadzones

https://forums.pcsx2.net/Thread-Feature-Request-Lilypad-s-Deadzone-removal-feature-in-PCSX2-2-0

It is also a feature that steaminput has

Using PCSX2 as a non steam game with steaminput, I was able to eliminate the issue. It would be nice to have the same options in RetroArch.

The issue names no files, tests, or entry points, so first locate RetroArch's analog input/deadzone handling and game-override settings. Define the anti-deadzone behavior as configurable input and output ranges, persist it as a game override, and verify it addresses the reported PCSX2 analog-stick problem.