Allow turning on/off all experimentalGameplay at once

[solvedDev]

Motivation

Most users don't want granular control over the specific experimental gameplay toggles and rather just want to always use all experiments or none at all.

Summary

Allow setting the "experimentalGameplay" property to true or false directly. If necessary, the project config parser can trivially transform the below syntax into the more verbose object syntax for backwards compatibility.

/**
 * Experimental gameplay the project intends to use.
 * Exact mapping of strings to experimental gameplay toggles needs to be specified separately.
 *
 * Set "experimentalGameplay" to a boolean value to turn on/off experimental gameplay completely.
 *
 * @example {"upcomingCreatorFeatures": true, "cavesAndCliffs": false}
 * @example true
 */
experimentalGameplay?: boolean | Record<string, boolean>