Rollup merge of rust-lang#126526 - Enselic:non-snake-case, r=jieyouxu

tests/ui/lint: Move 19 tests to new `non-snake-case` subdir

Mainly so that it is easier to only run all `non_snake_case`-lint-specific tests with:

    ./x test tests/ui/lint/non-snake-case

But also to reduce the size of the large `tests/ui/lint` directory. And rename some tests to pass tidy, and remove them from `src/tools/tidy/src/issues.txt`.

Author: GuillaumeGomez

src/tools/tidy/src/issues.txt

@@ -2760,7 +2760,6 @@ ui/lint/issue-1866.rs
 ui/lint/issue-19102.rs
 ui/lint/issue-20343.rs
 ui/lint/issue-30302.rs
-ui/lint/issue-31924-non-snake-ffi.rs
 ui/lint/issue-34798.rs
 ui/lint/issue-35075.rs
 ui/lint/issue-47775-nested-macro-unnecessary-parens-arg.rs
@@ -2769,15 +2768,13 @@ ui/lint/issue-54099-camel-case-underscore-types.rs
 ui/lint/issue-57410-1.rs
 ui/lint/issue-57410.rs
 ui/lint/issue-63364.rs
-ui/lint/issue-66362-no-snake-case-warning-for-field-puns.rs
 ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
 ui/lint/issue-79546-fuel-ice.rs
 ui/lint/issue-79744.rs
 ui/lint/issue-80988.rs
 ui/lint/issue-81218.rs
 ui/lint/issue-83477.rs
 ui/lint/issue-87274-paren-parent.rs
-ui/lint/issue-89469.rs
 ui/lint/issue-90614-accept-allow-text-direction-codepoint-in-comment-lint.rs
 ui/lint/issue-97094.rs
 ui/lint/issue-99387.rs