Expose two-way sync.

- Convert plugin DevSettings flag to settings panel feature
- Remove server feature, always enable write API

plugin/src/DevSettings.lua

@@ -25,14 +25,6 @@ local VALUES = {
 			[Environment.Test] = true,
 		},
 	},
-	UnstableTwoWaySync = {
-		type = "BoolValue",
-		values = {
-			[Environment.User] = false,
-			[Environment.Dev] = false,
-			[Environment.Test] = false,
-		},
-	},
 }
 
 local CONTAINER_NAME = "RojoDevSettings" .. Config.codename
@@ -140,10 +132,6 @@ function DevSettings:shouldTypecheck()
 	return getValue("TypecheckingEnabled")
 end
 
-function DevSettings:twoWaySyncEnabled()
-	return getValue("UnstableTwoWaySync")
-end
-
 function _G.ROJO_DEV_CREATE()
 	DevSettings:createDevSettings()
 end