Dynamically added root components

[guardrex]

Fixes #22690
Addresses #22045

• This PR's content and examples are based on the design in the PU issue. IF the design is correct ...

  • For the Blazor.renderComponent example, is "element" a DOM HTMLElement?
  • For <shopping-cart shopping-cart-id="..." />, are the dashes by convention ✨ for Pascal case component and parameter naming?

  If the design there isn't correct, what's the design for this feature?

• I don't see anything fleshed out for ...

  For server side Blazor there are security implications to this feature that we need to account for, like a limit on the number of components that can be rendered at any time or the list of components that can be rendered as well as their parameters.

  What guidance is required to cover security concerns 😨?

[SteveSandersonMS]

I'm happy to provide a draft of docs here but not today (or this week) as I'm currently focused on implementation and verification tasks. Hope that's OK. The product team will have much more focus on docs once RC2 winds up.

[guardrex]

Sure thing @SteveSandersonMS ... I was ordered to go ahead now generally. Let's get back to this one later.