Fix no supported codecs scenario

[mickel8]

Following Firefox behaviour, when there are no supported codecs in the offer, we will end up with empty transceivers lists on both sides after finishing negotiation.

See https://github.com/w3c/webrtc-pc/issues/2927

[codecov[bot]]

Codecov Report

Merging #61 (cd90b29) into master (528c056) will decrease coverage by 0.29%. Report is 3 commits behind head on master. The diff coverage is 72.72%.

:exclamation: Current head cd90b29 differs from pull request most recent head 0cfd170. Consider uploading reports for the commit 0cfd170 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #61 +/- ## ========================================== - Coverage 88.85% 88.57% -0.29% ========================================== Files 25 25 Lines 1059 1068 +9 ========================================== + Hits 941 946 +5 - Misses 118 122 +4 ``` | [Files](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc) | Coverage Δ | | |---|---|---| | [lib/ex\_webrtc/media\_stream\_track.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9tZWRpYV9zdHJlYW1fdHJhY2suZXg=) | `100.00% <ø> (ø)` | | | [lib/ex\_webrtc/peer\_connection/configuration.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9wZWVyX2Nvbm5lY3Rpb24vY29uZmlndXJhdGlvbi5leA==) | `89.85% <ø> (ø)` | | | [lib/ex\_webrtc/rtp/opus\_depayloader.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHAvb3B1c19kZXBheWxvYWRlci5leA==) | `0.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp/opus\_payloader.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHAvb3B1c19wYXlsb2FkZXIuZXg=) | `0.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp/vp8\_depayloader.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHAvdnA4X2RlcGF5bG9hZGVyLmV4) | `94.11% <ø> (ø)` | | | [lib/ex\_webrtc/rtp/vp8\_payload.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHAvdnA4X3BheWxvYWQuZXg=) | `90.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp/vp8\_payloader.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHAvdnA4X3BheWxvYWRlci5leA==) | `100.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp\_codec\_parameters.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHBfY29kZWNfcGFyYW1ldGVycy5leA==) | `100.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp\_sender.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHBfc2VuZGVyLmV4) | `100.00% <ø> (ø)` | | | [lib/ex\_webrtc/rtp\_transceiver.ex](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc#diff-bGliL2V4X3dlYnJ0Yy9ydHBfdHJhbnNjZWl2ZXIuZXg=) | `97.40% <100.00%> (+0.06%)` | :arrow_up: | | ... and [3 more](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc) | | ------ [Continue to review full report in Codecov by Sentry](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=continue&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc). > **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=elixir-webrtc) > `Δ = absolute (impact)`, `ø = not affected`, `? = missing data` > Powered by [Codecov](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=footer&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc). Last update [afa1851...0cfd170](https://app.codecov.io/gh/elixir-webrtc/ex_webrtc/pull/61?src=pr&el=lastupdated&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=elixir-webrtc). 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=elixir-webrtc).