An "Experimental features" area for trying features before they're ready for core

[thupsi]

The idea

A place in the control panel (core utility or first-party plugin) where developers can enable experimental features that Pixel & Tonic ships ahead of a final decision, try them in real projects, and give feedback. Each experimental feature has a simple on/off switch.

Why

Control panel changes are hard to judge from an issue or a screenshot. A switch for experimental features would give:

• Feedback with context. "I used X for a week and Y bothered me" beats a reaction to a description.
• Lower risk. A feature that's off by default can ship early without anyone depending on it.
• Room to decide later. Ideas can be tried by real users before they're approved, changed, or dropped.

Feedback

Each experimental feature links to where to discuss it. A "Send feedback" action could open a prefilled discussion with the feature name, Craft version and browser.

For reference, I've been using a small local module along these lines while testing the Craft 6 alpha. Screenshot below.