Enable manual tests in CI:

Fixes: RIPD-1575. Fix argument passing to runner. Allow multiple unit
test selectors to be passed via --unittest argument. Add optional
integer priority value to test suite list. Fix several failing manual
tests. Update CLI usage message to make it clearer.

src/test/ledger/Directory_test.cpp

@@ -441,7 +441,7 @@ struct Directory_test : public beast::unit_test::suite
     }
 };
 
-BEAST_DEFINE_TESTSUITE(Directory,ledger,ripple);
+BEAST_DEFINE_TESTSUITE_PRIO(Directory,ledger,ripple,1);
 
 }
 }