Fix: nextest cleanup race condition (#3334)

* remove unused trait fn `cleanup_test_dbs`

* *wip* solve test cleanup race condition

* check for exactly 63 chars in database name

* move base64 dependency

* change

* Use url_safe base64 encoding

* Assert quoting for database name

* refactor

* add mysql support?

* borrow

* fix borrows

* ensure quoting

* re-add trait cleanup_test_dbs

* fix mysql insert

* cargo lock

* use actual field

* cleanup converted path in sqlite

* replace dashes with underscore in db name

* refactor: remove redundant path conversion in cleanup_test and add db_name method

---------

Co-authored-by: Austin Bonander <austin.bonander@gmail.com>

sqlx-sqlite/src/testing/mod.rs

@@ -30,6 +30,10 @@ impl TestSupport for Sqlite {
     ) -> BoxFuture<'_, Result<FixtureSnapshot<Self>, Error>> {
         todo!()
     }
+
+    fn db_name(args: &TestArgs) -> String {
+        convert_path(args.test_path)
+    }
 }
 
 async fn test_context(args: &TestArgs) -> Result<TestContext<Sqlite>, Error> {