[testing] serial testing preserving terminal

[nthparameter]

This change does two things:

• add the serial_test crate to run selected tests serial rather than in parallel. This is done because they use global state so running them in parallel leads to race conditions and flaky results (sometimes they pass, sometimes they fail). Running them serialy avoids this flakiness.
• create a screen buffer within the test. This avoids changing the terminal (screen buffer) which is running the test. for example, a test that changes the terminal size to 20 x 20 can leave the developer running the test with a resized terminal. Creating a separate screen buffer for the test avoids this.