Added support of module-based unit tests for `scope_guard`.

* test/unit/jamfile: Added dependency on unit tests of `scope_guard`.
* test/unit/scope_guard/jamfile: Removed `compile`, `run` and `run-fail`
  targets.
* test/unit/scope_guard/scope_guard_run.cpp: Added test suites.
* test/unit/scope_guard/scope_guard_in_namespace_scope_run.cpp: Added test
  suites.
* test/unit/scope_guard/exception_guard_run.cpp: Added test suites.