bevy_ui: Apply #![deny(clippy::allow_attributes, clippy::allow_attributes_without_reason)]

[LikeLakers2]

Objective

• Deny the clippy::allow_attributes and clippy::allow_attributes_without_reason lints #17111

Solution

Set the clippy::allow_attributes and clippy::allow_attributes_without_reason lints to deny, and bring bevy_ui in line with the new restrictions.

Testing

cargo clippy --tests and cargo test --package bevy_ui were run, and no errors were encountered.

[LikeLakers2]

I am not proficient enough in bevy_ui to know if we should merge these expects that I added to crates/bevy_ui/src/layout/ui_surface.rs, or if we should wait until #17231 is fixed.

[LikeLakers2]

I was informed that there's already a PR for this: #16362

[StrikeForceZero]

in case you missed it from the last CI run

error: #[allow] attribute found
 --> crates/bevy_ui/src/render/debug_overlay.rs:57:3
  |
57 | #[allow(clippy::too_many_arguments)]
  |   ^^^^^ help: replace it with: `expect`

error: `allow` attribute without specifying a reason
  --> crates/bevy_ui/src/render/debug_overlay.rs:57:1
   |
57 | #[allow(clippy::too_many_arguments)]
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: try adding a reason at the end with `, reason = ".."`

Excluding my other comment and the above, everything looks good to me.

[LikeLakers2]

@StrikeForceZero I indeed missed it - because I intentionally ignored CI, thinking the errors were going to be about the #[expect(unreachable_code)]s.

I'll get it later today, as I can't check whether those need to be removed or replaced with expect()s without being at my dev computer.

[LikeLakers2]

Marked as ready for review per @alice-i-cecile - because whether my my PR is merged first, or @StrikeForceZero's PR is merged first, the other will have a minor merge conflict.