[Components] Enable a root component to be the entry point for component based apps

[javiercn]

This is a tracking issue for enabling applications that only use components end to end. Here we will discuss and track the work that needs to be done to enable this scenario:

• Support DOCTYPE declarations.
• Support a way to mark a component as a "root component" so that it can be used as the container for the entire app.
• Figure out a way to turn prerrendering on and off selectively.
• Figure out what component equivalents we need for things like the Environment tag helper, '~/' etc.
• Figure out specific integrations with endpoint routing.

[Andrzej-W]

The concept of "root component" is very nice. Please remember about SEO. Prerendered HTML page has to have correct title, description, metatags. More about this here: https://github.com/aspnet/Blazor/issues/1311#issuecomment-413046895

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[mkArtakMSFT]

Closing as this should be already done.