Expanding signed route generation capabilities

[irealworlds]

I think it would be useful to expand signed uri generation to expose a way for working with actions, not only for named routes.
Currently, I find myself having to implement my own service for this behaviour (or use named routes anyway only for specific routes that need signatures)

Moreover, another thing that could be explored is splitting the UrlGenerator interface into an offshoot SignedUrlGenerator to keep the contract from growing too big (not really essential to the main proposal, but an idea to consider)