Construct DeprecatedRoute annotations using named arguments

[philiprabbett]

Deprecate creating instances of the DeprecatedRoute annotation class by passing an array of parameters, use named arguments instead.

[marco-giannetti]

Thank you for the issue @philiprabbett, it sounds interesting. We'll come back to it as soon as we have time! If you want to give it a go in the meantime, PRs are welcome for this project!