RTC-446 Notify turn off simulcast layer

[Rados13]

Blocked by: https://github.com/jellyfish-dev/membrane-webrtc-js/pull/51 and https://github.com/jellyfish-dev/membrane_webrtc_plugin/pull/121

[codecov[bot]]

Codecov Report

Merging #352 (e8838c6) into master (ba53dd3) will increase coverage by 0.50%. The diff coverage is 74.46%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #352 +/- ## ========================================== + Coverage 52.95% 53.45% +0.50% ========================================== Files 53 53 Lines 2404 2443 +39 ========================================== + Hits 1273 1306 +33 - Misses 1131 1137 +6 ``` | [Files](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev) | Coverage Δ | | |---|---|---| | [engine/lib/membrane\_rtc\_engine/endpoint.ex](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-ZW5naW5lL2xpYi9tZW1icmFuZV9ydGNfZW5naW5lL2VuZHBvaW50LmV4) | `61.53% <100.00%> (+6.99%)` | :arrow_up: | | [engine/lib/membrane\_rtc\_engine/engine.ex](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-ZW5naW5lL2xpYi9tZW1icmFuZV9ydGNfZW5naW5lL2VuZ2luZS5leA==) | `83.27% <100.00%> (+2.61%)` | :arrow_up: | | [engine/lib/membrane\_rtc\_engine/track.ex](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-ZW5naW5lL2xpYi9tZW1icmFuZV9ydGNfZW5naW5lL3RyYWNrLmV4) | `33.33% <ø> (-4.17%)` | :arrow_down: | | [webrtc/lib/webrtc/media\_event.ex](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-d2VicnRjL2xpYi93ZWJydGMvbWVkaWFfZXZlbnQuZXg=) | `19.75% <0.00%> (-1.30%)` | :arrow_down: | | [webrtc/lib/webrtc\_endpoint.ex](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev#diff-d2VicnRjL2xpYi93ZWJydGNfZW5kcG9pbnQuZXg=) | `0.00% <0.00%> (ø)` | | ... and [3 files with indirect coverage changes](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev) ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). > **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). Last update [ba53dd3...e8838c6](https://app.codecov.io/gh/jellyfish-dev/membrane_rtc_engine/pull/352?src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=jellyfish-dev).