ALPS-700 - Omnitone crash

[aberthet-gpsw]

When in a story with multiple scenes using omnitone/ambisonic sounds the library is initialized at each scene on the first time we visit them and if we revisit them again it throws an error.

This PR fixes this problem.

[sw-team-release-gpsw]

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1 out of 4 committers have signed the CLA.

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:x: aberthet-gpsw
:x: Benjamin Baudel
:x: benjamin

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[bbaudel]

Still WIP status.

• Works well with image scene with background sound between scenes
• Works well with videos scenes with ambisonics
• Don't work when reaching a video scene after an image scene which contains ambisonics as scene sound