EwomsAddApplication: allow to only compile it with this macro, but do not run tests

if tests are available for the application, EwomsAddTest() must be
called explicitly:

```
EwomsAddApplication(AppName ...)
EwomsAddTest(TestName1 EXEC_NAME AppName DEPENDS_ON AppName NO_COMPILE ...)
EwomsAddTest(TestName2 EXEC_NAME AppName DEPENDS_ON AppName NO_COMPILE ...)
...
```