Action-Input Manager

## Goal Description

Mapping inputs (keys, buttons) to actions (run, jump, undo, toggle wireframes) is vital functionality for Bevy applications and first-party tooling. However, doing this well is shockingly hard. This goal covers the upstreaming or creation of an input manager that handles rebinding, serialization, and conflicts across gamepad, mouse and keyboard inputs. Axislike and buttonlike actions must be supported, but additional, more complex action types may be included as part of this work.

Previously discussed in #435.

## Goal Status

This is a potential [Bevy Project Goal](https://bevy.org/learn/contribute/project-information/project-goals/). Its state on the [Project Goals Board](https://github.com/orgs/bevyengine/projects/23/views/1) determines if it is Proposed, Postponed, Blocked (Approved), Inactive (Approved), Active (Approved), Completed, or Declined.

- **Staffing SMEs**: Not yet staffed
- **Working Group Link**: Working Group not yet formed
- **Design Documents**: Design documents not yet written