1561922a12
translations(rustc_session): migrates rustc_session to use SessionDiagnostic - Pt. 2
# Description
This is the second part of the `rustc_session` [migration](https://github.com/rust-lang/rust/issues/100717#issuecomment-1220279883).
**Please only review this [commit](5018581957) that belongs to the part 2. The other ones are from the PR [#100753](https://github.com/rust-lang/rust/pull/100753) that is not yet merged.**
In this PR, we migrate the files `session.rs` and `config.rs`.
Please not that we have to `allow` the lints rules in some functions from `session.rs` because they are (at least I believe) part of the diagnostic machinery.