[WIP] Create custom behavior for RouteNotFoundException

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #10
| License       | MIT
| Doc PR        | need to be done

That's my starting point to work on this issue.

this param should be a list of routes i think, no? does it have to be a RouteObjectInterface or can it be any route?

and some doc to explain what this is for would help. you sure you want this private and not protected? might be something a user needs to customize...