Add tests for trailing slash prefix-suffix conflict bug

Add test cases to unveil an issue where the order of adding routes like
/x20/f{a}o/{*path} and /x20/f{a}o could result in a conflict.

Signed-off-by: Changyuan Lyu <changyuanl@google.com>

Author: Lencerf

tests/insert.rs

@@ -257,6 +257,10 @@ fn prefix_suffix_conflict() {
         ("/x16/prefix{a}suffix", Ok(())),
         ("/x17/prefix{a}/z", Ok(())),
         ("/x18/prefix{a}/z", Ok(())),
+        ("/x19/f{a}o", Ok(())),
+        ("/x19/f{a}o/{*path}", Ok(())),
+        ("/x20/f{a}o/{*path}", Ok(())),
+        ("/x20/f{a}o", Err(conflict("/x20/f{a}o/{*path}"))),
     ])
     .run()
 }