Implement Peer's renegotiation synchronization (#27)

[evdokimovs]

Part of #27

Requires #105

Synopsis

Currently, Peer updates (such as MediaTrack adding) which are needs renegotiation, may be performed only on Peer in Stable state. But in some cases Peer update may be performed in the not Stable state, so we should add functional of delayed Peer updating if it not in Stable state.

Solution

All actions which are needs renegotiation now will be delayed actions (named Job). So Job wouldn't executed on function call, but will be called only when Peer will be in Stable state. All Jobs will be stored in the Peer's VecDeque and will be executed in the right order.

When MediaTrack deleting will be implemented, we also should implement cleaning unpublished overlapping actions from the Peer. For example, if Job which creates MediaTrack was pushed into Jobs queue and after it Job which deletes this MediaTrack also was published into Job queue. This is overlapping Jobs and they should be ignored, because they doesn't make sense.

Checklist

• Created PR:
  • In draft mode
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  • Name contains issue reference
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• Documentation is updated (if required)
• Tests are updated (if required)
• Changes conform code style
• CHANGELOG entry is added (if required)
• FCM (final commit message) is posted
  • and approved
• Review is completed and changes are approved
• Before merge:
  • Milestone is set
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  • WIP: prefix is removed
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