feat: Shared DOM

[linkdotnet]

Pull request description

This PR tackles mainly #983 - where we try to have a shared dom. This approach works as follows:

1. When creating the HTML, we add additional comments with the component id in the markup (that might break tests!! that rely on string comparison not utilizing anglesharp)
2. We keep a map of componentId -> NodeList (basically where are the boundaries per component)
3. When using Nodes from IRenderedComponent<T> we try to find the root and return it's nodelist! Therefore all children share basically the same node list

This basically "fixes" the issue in 983. More of an idea / play than something we have to go forward with.

[egil]

Exciting! You are taking another crack at this, waiting to see what you come up with :)