Add getters and setters for InputAxis and ButtonSettings (bevyeng…

…ine#6088)

# Objective
Fixes bevyengine#3418

## Solution

Originally a rebase of bevyengine#3446.  Work was originally done by mfdorst, who should receive considerable credit.  Then the error types were extensively reworked by targrub.

## Migration Guide

`AxisSettings` now has a `new()`, which may return an `AxisSettingsError`.
`AxisSettings` fields made private; now must be accessed through getters and setters.  There's a dead zone, from `.deadzone_upperbound()` to `.deadzone_lowerbound()`, and a live zone, from `.deadzone_upperbound()` to `.livezone_upperbound()` and from `.deadzone_lowerbound()` to `.livezone_lowerbound()`.
`AxisSettings` setters no longer panic.
`ButtonSettings` fields made private; now must be accessed through getters and setters.
`ButtonSettings` now has a `new()`, which may return a `ButtonSettingsError`.

Co-authored-by: targrub <62773321+targrub@users.noreply.github.com>

crates/bevy_input/Cargo.toml

@@ -22,3 +22,4 @@ bevy_reflect = { path = "../bevy_reflect", version = "0.9.0-dev" }
 
 # other
 serde = { version = "1", features = ["derive"], optional = true }
+thiserror = "1.0"