add set_group_moderation_flags endpoint

[julianjelfs]

No description provided.

[github-actions]

canbench 🏋 (dir: .)

./canbench_results.yml is up to date ✅

---------------------------------------------------

Benchmark: push_simple_text_messages
  total:
    instructions: 207.06 M (0.26%) (change within noise threshold)
    heap_increase: 13 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------

Benchmark: add_reactions
  total:
    instructions: 1.24 B (0.05%) (change within noise threshold)
    heap_increase: 4 pages (no change)
    stable_memory_increase: 0 pages (no change)

---------------------------------------------------