Improve HRESULT ergonomics

[kennykerr]

As you might expect, the HRESULT type is pivotal in the implementation of the bindings produced by windows-rs, whether it's the various implementation inside windows-core or the mountain of bindings produced by the windows-bindgen crate. Early on, I used HRESULT helpers to bootstrap and simplify API call generation but those were never very consistent with the Rust standard library. Here I'm aiming to make that a little less confusing and more consistent with prior art. I also hope to decouple it from the internals of windows-core and make it more generally useful.

Notably, the following has changed:

• The and_then method is now called map that behaves much like Result::map.
• A new and_then method is added that behaves much like Result::and_then.
• The and_some method is gone. This was mostly used internally, but can be implemented in terms of and_then if needed.
• The from_abi method is gone. This was mostly used internally, but can be implemented in terms of and_then or map.