Use getDisplayMedia() and DisplayMediaStreamConstraints from 'web_sys' crate (#27)

[evdokimovs]

Part of #27

Synopsis

Currently we're making gDM requests by inlined JS code, because until this moment web_sys haven't bindings for it. But in 0.3.47 version they was added. So now we should use web_sys bindings instead.

Solution

Remove get_display_media function from medea_jason::media::manager and use web_sys bindings instead.

Checklist

• Created PR:
  • [x] In draft mode
  • [x] Name contains Draft: prefix
  • [x] Name contains issue reference
  • [x] Has k:: labels applied
  • [x] Has assignee
• [x] Documentation is updated (if required)
• [x] Tests are updated (if required)
• [x] Changes conform code style
• [x] CHANGELOG entry is added (if required)
• [x] FCM (final commit message) is posted
  • [x] and approved
• [x] Review is completed and changes are approved
• Before merge:
  • [x] Milestone is set
  • [x] PR's name and description are correct and up-to-date
  • [x] Draft: prefix is removed
  • [x] All temporary labels are removed

[evdokimovs]

FCM

Use getDisplayMedia() and DisplayMediaStreamConstraints from 'web_sys' crate (#177, #27)