chore(video-conf): conference data model, server service & API (1/4) - #41934

No issues found. Git change coverage: 50 change(s), 48 regular HEAD file(s) prepared, 2 deletion(s) not applicable, 0 unsupported, 0 unavailable. Spectre coverage incomplete: selected 5, scanned 5, skipped 1, oversized 0, capped 42, truncated 0, failed 0, invalid 0, rejected 0, repairs 0, repaired responses 0, repaired findings 0, cancelled 0, rate-limited 0, concurrency-limited 0, circuit-open 0. Reason: file-cap-exceeded.