Support content on transport components

[loreanvictor]

Right now, you cannot provide the content of a transport component during static rendering phase, which is pretty limiting. I suspect it should actually be feasible:

• During static rendering, render the content to an intermediate element.
• Pass the HTML string representation of that element to transport script.
• During dynamic rendering, render the HTML string using DOM APIs directly (_innerHTML)
• Ensure that scripts are going to execute properly (so nested transported components are properly populated)
• Pass the resulting DOM to the (parent) transported component.