lint / ImproperCTypes: better handling of indirections, take 2

[niacdoial]

This PR tries to re-add the changes in #131669 (which were reverted in #134064 after one (1) nightly),
and adds better coverage of ty_kinds:

• in the take-1-added TypeSizedness enum and its construction
• in a new test file

The changes in the original PR aim to make ImproperCTypes/ImproperCTypesDefinitions produce better warnings when dealing with indirections (Box, &T, *T), especially for those to DSTs.

r? workingjubilee (because you reviewed the first attempt)

[niacdoial]

(
hi Jubilee, I'm back at this again!
I know this is not the best time of year to add PRs, so I'm fine with postponing this if you don't feel like tackling it these upcoming weeks.
In any case, have some nice end-of-year festivities, if you celebrate any!
)

[niacdoial]

ah, and before I forget: a small part of the new test file is commented out because it hits ICE #134587, but there should be more than decent coverage anyway

[workingjubilee]

unfortunately the lint needs to be gutted and rewritten.

[workingjubilee]

Also while I was possibly having a mild case of get-there-itis and thus mostly tried to just make sure things were coherent, I would prefer all new code for the lint be in compiler/rustc_lint/src/types/improper_ctypes.rs.