This make it coherent with typing of Router.createUrlTree to which
those inputs are directly forwarded to. And hence it allow to pass
`undefined`, `null` or a value to the routerLink directive.
BREAKING CHANGE: in most cases this should not break, but if you were
accessing the values of `queryParams`, `fragment` or `queryParamsHandling`
you might need to relax the typing to also accept `undefined` and `null`.
Signed-off-by: Adrien Crivelli <adrien.crivelli@gmail.com>
PR Close#39151