Make `--collator` reusable and imply `--validator` (#380)

* Reusable RunCmd struct

* wire new run command through service

* Fill in the rest of the methods

* attempt normalization

* Settle on the borrowing approach

* add the normalize call

* bump substrate

* Update client/cli/src/lib.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Update docs

* Update client/cli/src/lib.rs

Co-authored-by: Bastian Köcher <[email protected]>

Co-authored-by: Bastian Köcher <[email protected]>