Add run-rustfix for deref_addrof lint
* renames `tests/ui/reference.{rs,stderr}` to
`tests/ui/deref_addrof.{rs,stderr}
* Moves small part of the testfile to a separate file as the lint
triggered again on the fixed code (as intended)
* Adds `// run-rustfix` to `tests/ui/deref_addrof.rs`
cc #3630
1936368da1