[pg] Run simple docker test per PR

[rekby]

• [x] Show selected tests
• [x] Handle deselect tests
• [x] Build and run test image
• [ ] Parse test results to pytest results
• [ ] Start/stop container for the test
• [ ] Autoselect free port for postgres and set the option

Write python wrapper for docker containers test.

The wrapper must allow minimum two modes:

• run all teest
• run one test through ya make -F

[rekby]

Hooks

def pytest_generate_tests(metafunc): ...

and def pytest_deselected(items): ...

allow to generate test names and detect what of them are filtered.

Hook spec

[rekby]

Work within folder: https://github.com/rekby-forks/ydb/tree/pg-tests/ydb/tests/postgres_integrations