refactor jest setup to improve unit/integration test executions (#2322)

* fix test:integration command to run tests directly under ./test/integration

* refactor jest setup to have separate config files for integration and unit tests

packages/xrpl/test/connection.test.ts

@@ -437,6 +437,7 @@ describe('Connection', function () {
       try {
         await clientContext.client.connect()
       } catch (error) {
+        // @ts-expect-error -- error.message is expected to be defined
         expect(error.message).toEqual(
           "Error: connect() timed out after 5000 ms. If your internet connection is working, the rippled server may be blocked or inaccessible. You can also try setting the 'connectionTimeout' option in the Client constructor.",
         )