Refactor header-checker tests

- Rename the unit test class to HeaderCheckerTest.
- Create/delete temporary directory in setUp/tearDown.
- Move make_and_copy_reference_dumps from gen_all.py to test.py.
- Remove duplicate constant paths.
- Add default arguments to LsdumpModule.
- Fix coding style.

Bug: 117582158
Test: ./gen_all.py
Test: ./test.py
Change-Id: I6345a10da5431e8057e4a9321ecce4168b7d5292