Tweak output of import suggestions
When both `std::` and `core::` items are available, only suggest the `std::` ones. We ensure that in `no_std` crates we suggest `core::` items.
Ensure that the list of items suggested to be imported are always in the order of local crate items, `std`/`core` items and finally foreign crate items.
Tweak wording of import suggestion: if there are multiple items but they are all of the same kind, we use the kind name and not the generic "items".
Fix#83564.
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