Add path constants to `test` module and use them in different test suites
instead of own dups of the same code:
- TOP_SRC_DIR : ScyllaDB's source code root directory
- TEST_DIR : the directory with test.py tests and libs
- BUILD_DIR : directory with ScyllaDB's build artefacts
Add TestSuite.log_dir attribute as a ScyllaDB's build mode subdir of a path
provided using `--tmpdir` CLI argument. Don't use `tmpdir` name because it
mixed up with pytest's built-in fixture and `--tmpdir` option itself.
Change default value for `--tmdir` from `./testlog` to `TOP_SRC_DIR/testlog`
Refactor `ResourceGather*` classes to use path from a `test` object instead of
providing it separately.
Move modes constants to `test` module and remove duplications.
Move `prepare_dirs()` and `start_3rd_party_services()` from `pylib.util` to
`pylib.suite.base` to avoid circular imports (with little refactoring to
use `pathlib.Path` instead of `str` as paths.)
Also, in some places refactor to use f-strings for formatting.
Add the possibility to run boost test from pytest.
Boost facade based on code from https://github.com/pytest-dev/pytest-cpp, but enhanced and rewritten to suite better.
Code based on https://github.com/pytest-dev/pytest-cpp. Updated, customized, enhanced to suit current needs.
Modify generate report to not modify the names, since it will break
xdist way of working. Instead modification will be done in post collect
but before executing the tests.
