Add HttpRequestBase.Files and supporting types

[sdekock]

In PR #103 the types to handle file upload were added: Files property on HttpRequest and HttpPostedFile class.

These should also be created in the *Base variants: Files property in HttpRequestBase and a HttpPostedFileBase class.

[sdekock]

To be considered as part of #91 ?

[twsouthwick]

Let's keep it separate - #91 will be separated out into new issues (all features from that that will be addressed for v1 have been at this point). Can you share the full API shape you want to enable here?

[sdekock]

Can you share the full API shape you want to enable here?

The Files property on the HttpRequestBase class and Files property on the HttpRequestWrapper class
And supporting types:
HttpFileCollectionBase
HttpFileCollectionWrapper
HttpPostedFileBase
HttpPostedFileWrapper

Same functionality that was exposed as per PR #103 on HttpRequest, but then on the *Base variants plus the Wrapper classes.

I already made an attempt of implementing this here: main...sdekock:systemweb-adapters:sdk/requestbase-files
But I have not been able to test it, so I have not yet created a PR. I can finish it if you want to ...

[adityamandaleeka]

@sdekock Sure, a PR would be welcomed. At this point it likely wouldn't make it into the RC 1 release but we would get it into post-1.0.