WIXFEAT:4505 - WixHttpExtension for URL reservations

I tried to find all the places to add the new extension and implement everything, but I might have missed something.

I would like to port this back to v3.x.
Ideally this implementation detail of using a `*` to define a SID should be hidden behind an attribute. Take a look at the `ServiceDependency` element's `Group` attribute for an example.