Inject measure funcs directly into UiSurface

[ickshonpe]

What problem does this solve or what need does it fill?

Atm we set measure funcs indirectly using the ContentSize component. If a new measure is required for some content the content's update system has to wrap the measure inside a NodeMeasure enum which is then wrapped inside an Option. In ui_system_layout we take it out the option and pass it taffy which stores it in its node_context_data slotmap. This seems unnecessarily overcomplicated.

What solution would you like?

Instead the systems that update the measure funcs could just retrieve UiSurface and call its update_node_context method to inject the measure directly.