Rollup merge of #104363 - WaffleLapkin:bonk_box_new, r=Nilstrieb

Make `unused_allocation` lint against `Box::new` too

Previously it only linted against `box` syntax, which likely won't ever be stabilized, which is pretty useless. Even now I'm not sure if it's a meaningful lint, but it's at least something :shrug:

This means that code like the following will be linted against:
```rust
Box::new([1, 2, 3]).len();
f(&Box::new(1)); // where f : &i32 -> ()
```
The lint works by checking if a `Box::new` (or `box`) expression has an a borrow adjustment, meaning that the code that first stores the box in a variable won't be linted against:
```rust
let boxed = Box::new([1, 2, 3]); // no lint
boxed.len();
```

0 files changed, 0 insertions, 0 deletions