Auto merge of #112071 - WaffleLapkin:group-rfcs-tests, r=oli-obk

Group rfcs tests

This moves all RFC tests to `tests/ui/rfcs/rfc-NNNN-title-title-title/...`

I had to rename some tests due to conflicts, but otherwise this is just a move.

Author: bors

src/tools/tidy/src/ui_tests.rs

@@ -11,7 +11,7 @@ use std::path::{Path, PathBuf};
 const ENTRY_LIMIT: usize = 900;
 // FIXME: The following limits should be reduced eventually.
 const ISSUES_ENTRY_LIMIT: usize = 1898;
-const ROOT_ENTRY_LIMIT: usize = 891;
+const ROOT_ENTRY_LIMIT: usize = 871;
 
 const EXPECTED_TEST_FILE_EXTENSIONS: &[&str] = &[
     "rs",     // test source files