feat(ffi) Add create poll API

[alfogrillo]

Fix #2388

Body example forPUT _matrix/client/v3/rooms/{room-id}/send/org.matrix.msc3381.poll.start

{
  "org.matrix.msc1767.text": "Do you like polls?\n1. Yes\n2. No\n3. Maybe",
  "org.matrix.msc3381.poll.start": {
    "answers": [
      {
        "id": "0",
        "org.matrix.msc1767.text": "Yes"
      },
      {
        "id": "1",
        "org.matrix.msc1767.text": "No"
      },
      {
        "id": "2",
        "org.matrix.msc1767.text": "Maybe"
      }
    ],
    "kind": "org.matrix.msc3381.poll.disclosed",
    "max_selections": 2,
    "question": {
      "org.matrix.msc1767.text": "Do you like polls?"
    }
  }
}

[julioromano]

LGTM for what it's worth :D

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.01% 🎉

Comparison is base (3d3021e) 77.84% compared to head (96e4e22) 77.85%.
Report is 33 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2391      +/-   ##
==========================================
+ Coverage   77.84%   77.85%   +0.01%     
==========================================
  Files         176      176              
  Lines       18698    18698              
==========================================
+ Hits        14555    14558       +3     
+ Misses       4143     4140       -3     

see 1 file with indirect coverage changes

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