Add ::clientModelToInput() to ComponentSourceInterface, the inverse of ::inputToClientModel()

Overview

In #3489899: Add support for global regions we added this code

-      if (isset($hydrated[$component_instance_uuid]['props'])) {
-        $model[$component_instance_uuid] = $hydrated[$component_instance_uuid]['props'];
+      if (isset($hydrated[$component_instance_uuid])) {
+        $model[$component_instance_uuid] = $hydrated[$component_instance_uuid]['props'] ?? $hydrated[$component_instance_uuid]['settings'];

However that hard-codes knowledge of how a component source plugin maps its hydrated values to the client model

Proposed resolution

Add a new method to ComponentSourceInterface and move this logic into each of the respective plugins

User interface changes

None.