Add AV1 transcoding support (#8491)

* Add AV1 transcoding support

- AV1 encoding on CPU via SVT-AV1 (libsvtav1 in ffmpeg)
- Supports CRF and optionally capped CRF (max bitrate)
- Tested playback successfully in Chrome Win+Android, Firefox Win+Linux, Android app

* AV1: Add support for encoding threads option

* Revert previous commit; specifying params multiple times is bad

We need to specify all svtav1-params at once, so putting the thread option into getThreadOptions is not possible.

* AV1: Override VAAPI getSupportedCodecs as it does not yet support AV1 unlike nvenc, qsv, amf

* Change BaseHWConfig supported codecs to only H264/HEVC

Configs that support VP9 and/or AV1 need to override getSupportedCodecs()

* Set SVT-AV1 threads with svtav1-params, remove duplicate block in NVENCConfig

* AV1Config: Fix empty svtav1-params array being added to options

* add tests

* update api

* allow crf-based two-pass mode

* formatting

* suggest 35

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Co-authored-by: mertalev <101130780+mertalev@users.noreply.github.com>

open-api/typescript-sdk/src/fetch-client.ts

@@ -2984,7 +2984,8 @@ export enum AudioCodec {
 export enum VideoCodec {
     H264 = "h264",
     Hevc = "hevc",
-    Vp9 = "vp9"
+    Vp9 = "vp9",
+    Av1 = "av1"
 }
 export enum CQMode {
     Auto = "auto",