This change simplifies IFormatFilter's API and removes the dependency on
IActionContext accessor.
The old API for IFormatFilter required computing state based on the
current request as part of the constructor, which in turn implied the use
of a context accessor. This isn't really needed. I didn't preserve caching of
the 'format' as that seems like an early optimization.
Abstractions - Core MVC extensibility
Controllers - MVC implementations of .Abstractions and supporting
contracts
Infrastructure - General purpose support APIs. Metadata APIs that don't
fit clearly with a feature or with .Abstraction
Ryan Nowak
Pranav K