Refactor allow to expect (#41586)

Replace `allow` with `expect` lints for `unused`, `unsafe_code`,
`dead_code`, and `non_upper_case_globals`.

Testing: So far just check it compiled on `x86_64-linux` on NixOS. Need
to use the module `system.fontconfig.enable = true;` I think in my NixOS
config.
Part of: #40383 

Searching `allow\(.*\)` for `.rs` files shows the following. for
(total_results:total_files) went from `707:386` to `675:368`, a
reduction of `32:18`.

How many files is too many files per PR? I feel like the 20-30 I have is
too big.

---------

Signed-off-by: Wayne Van Son <waynevanson@gmail.com>

support/crown/tests/compile-fail/missing_allow_in_rc.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 use std::rc::Rc;
 

support/crown/tests/compile-fail/missing_unrooted_interior.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 #[crown::unrooted_must_root_lint::must_root]
 struct MustBeRooted;

support/crown/tests/compile-fail/missing_unrooted_interior_on_trait.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 trait TypeHolderTrait {
     #[crown::unrooted_must_root_lint::must_root]

support/crown/tests/run-pass/alias-projection-ignored.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 fn main() {}
 

support/crown/tests/run-pass/allow_interior_trait.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 trait TypeHolderTrait {
     #[crown::unrooted_must_root_lint::must_root]

support/crown/tests/run-pass/allow_trait_in_rc.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 use std::rc::Rc;
 

support/crown/tests/run-pass/allowed_interior.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 #[crown::unrooted_must_root_lint::must_root]
 struct MustBeRooted;

support/crown/tests/run-pass/cfg_crown.rs

@@ -3,7 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 //@rustc-env:RUSTC_BOOTSTRAP=1
 
-#![allow(dead_code)]
+#![expect(dead_code)]
 
 const _: () = assert!(cfg!(crown), "cfg(crown) not set!");