Provide more Debug information for indexed types.

[ouz-a]

With this rust-lang/rust#115534 we will be able to get nicer debug information for DefId, and according to @oli-obk rust-lang/rust#115534 (comment), we need to do this for other indexed types as well (Place would be good contender imo).

Edit: Place doesn't need better Debug, but assignments involving Const needs to be fixed they look overly verbose right now

[ouz-a]

Made ty::Ty Debug better here rust-lang/rust#115605

[ouz-a]

With this rust-lang/rust#115772 Span is also indexed type and it prints full debug information.