warn for useless parameter storage classes

[WebFreak001]

See https://dlang.org/spec/function.html#parameters

Storage Class	Description
scope	The parameter must not escape the function call (e.g. by being assigned to a global variable). Ignored for any parameter that is not a reference type.
return	Parameter may be returned or copied to the first parameter, but otherwise does not escape from the function. Such copies are required not to outlive the argument(s) they were derived from. Ignored for parameters with no references. See Scope Parameters.

[rikkimax]

It should also warn on scope return, as the correct order recognized by the compiler is return scope. Same order for ref.

This is something I keep doing wrong.

However on the function itself its a lot more complicated and there is no "correct" order: https://dlang.org/spec/function.html#ref-return-scope-parameters