[Change]: [1.93] LUB coercions now correctly handle function item types, and functions with differing safeties

### Change description

LUB coercions now correctly handle function item types, and functions with differing safeties

### Area

type inference

### Category

New content

### FLS Paragraph ID

_No response_

### Change description (extended)

[LUB coercions now correctly handle function item types, and functions with differing safeties](https://github.com/rust-lang/rust/pull/148602)