Feature: Cast or convert to InProcess version of wrappers

[KristofferStrube]

As described in KristofferStrube/Blazor.FileSystemAccess#23 we use a new structure that has InProcess variants of wrapper classes that have synchronous methods or attributes.

I would want for it to be possible to convert the Blazor Server wrapper classes to the extended Blazor WASM InProcess variants through a cast or some method like AsInProcess(), ToInProcessWrapper. This might be possible to do by defining an explicit cast as an IJSObjectReference can be casted to an IJSInProcessObjectReference explicitly. The thing that might not be possible to do through a cast as that is synchronous is to create the inProcessHelper which is needed for the InProcess variants.