those get handled properly in strip-hidden anyway

By introducing a new map that tracks the errors reported and the
`Place`s that spawned those errors against the move out that the error
was referring to, we are able to silence duplicate errors by emitting
only the error which corresponds to the most specific `Place` (that which
other `Place`s which reported errors are prefixes of).

This generally is an improvement, however there is a case -
`liveness-move-in-while` - where the output regresses.

Apparently copyright notices are no longer necessary apparently.
(See #43498 and #53654.)

... and also proc macro attributes used together with test/bench.

The way it defines implementations is unrealistic though.

(Includes a couple variations on the theme. I confirmed that the ones
in `in_expression_position` and `what_if_we_use_panic_directly_in_expr`
both failed back on "rustc 1.30.0-nightly (0f063aef 2018-09-03)".)

rustc_resolve: don't treat uniform_paths canaries as ambiguities unless they resolve to distinct Def's.

This adds a suggestion to the `invalid_crate_types` lint.

The suggestion is based on the Levenshtein distance to existing crate
types. If no suggestion is found it will show the lint without any
suggestions.

Advised by @estebank.