Move renderer initialization from build time to RenderStartup

[janhohenheim]

Objective

• Transitively part of Split the Window component for more granular change detection #19644
• Required for Move Window creation from plugin build time to PreStartup #20019, which is required for Initialize Window by observer instead of by plugin fields #20018
• Split off so that a bisect can find this
  • If you just bisected this PR: sorry!

I'd like to move the primary window creation into Startup for reasons detailed in the linked PRs, but I cannot do so, since RenderApp needs it in its own build

Solution

• Move the relevant code into RenderStartup

Testing

• TODO

[alice-i-cecile]

Swap the label over once CI is green please :)

[janhohenheim]

I need some scheduling help.
My goal is to move the Window creation from the WindowPlugin::build method into PreStartup.
To do that, I also need to migrate some parts of the RenderPlugin, as they depend on Window being present on build.
The issue is that the part in question is the code that initializes the RenderResources in an async fashion. Right now, the returns false in RenderPlugin::ready until that async code is done, then inserts the relevant resources from RenderResources into the World in RenderPlugin::finish
But if I move the related RenderResources initialization code into PreStartup, I cannot insert those resources until that async task is done, which might be at any time after Startup or RenderStartup 🤔
For context, the information inside the PrimaryWindow is used for RequestAdapterOptions::compatible_surface. Specifically, the RawHandleWrapperHolder is used to create the surface

[JMS55]

Can we wait to get DLSS in first? I don't want to have to rebase the whole rendering initialization code again, it's very difficult :(

[janhohenheim]

@JMS55 sure! I don't know how to proceed anyways for now :D

[janhohenheim]

Blocked on #19864