fix: handle AC-4 immersive stereo (IMSA) in HLS and DASH spatial audio detection

[avelad]

More info:
https://ott.dolby.com/OnDelKits/AC-4/Dolby_AC-4_Online_Delivery_Kit_1.5/Documentation/Specs/AC4_HLS/help_files/topics/hls_playlist_c_codec_indication_ims.html
https://ott.dolby.com/OnDelKits/AC-4/Dolby_AC-4_Online_Delivery_Kit_1.5/Documentation/Specs/AC4_DASH/help_files/topics/MPEG_dynmc_adpt_strmg_c_mpd_for_ims.html

[shaka-bot]

Bundle Size Report for PR #10007

File	HEAD	Base	Diff
controls.css	23.6 KiB (4.9 KiB)	23.6 KiB (4.9 KiB)	0.0 KiB
demo.compiled.debug.js	257.6 KiB (51.7 KiB)	257.6 KiB (51.7 KiB)	0.0 KiB
demo.compiled.js	257.6 KiB (51.7 KiB)	257.6 KiB (51.7 KiB)	0.0 KiB
demo.css	170.3 KiB (27.8 KiB)	170.3 KiB (27.8 KiB)	0.0 KiB
locales.js	42.6 KiB (10.6 KiB)	42.6 KiB (10.6 KiB)	0.0 KiB
receiver.compiled.debug.js	148.4 KiB (24.1 KiB)	148.4 KiB (24.1 KiB)	0.0 KiB
receiver.compiled.js	148.4 KiB (24.1 KiB)	148.4 KiB (24.1 KiB)	0.0 KiB
shaka-player.compiled-es2021.debug.js	1251.5 KiB (307.1 KiB)	1251.4 KiB (307.1 KiB)	+0.1 KiB
shaka-player.compiled-es2021.js	663.2 KiB (220.8 KiB)	663.1 KiB (220.7 KiB)	+0.1 KiB
shaka-player.compiled.debug.js	1522.7 KiB (348.4 KiB)	1522.5 KiB (348.4 KiB)	+0.2 KiB
shaka-player.compiled.js	766.7 KiB (248.3 KiB)	766.6 KiB (248.3 KiB)	+0.1 KiB
shaka-player.dash-es2021.debug.js	920.2 KiB (231.0 KiB)	920.1 KiB (231.0 KiB)	+0.1 KiB
shaka-player.dash-es2021.js	456.3 KiB (155.8 KiB)	456.2 KiB (155.7 KiB)	+0.1 KiB
shaka-player.dash.debug.js	1117.4 KiB (261.2 KiB)	1117.3 KiB (261.2 KiB)	+0.1 KiB
shaka-player.dash.js	530.0 KiB (175.6 KiB)	529.8 KiB (175.6 KiB)	+0.1 KiB
shaka-player.experimental-es2021.debug.js	1620.9 KiB (387.7 KiB)	1620.7 KiB (387.7 KiB)	+0.1 KiB
shaka-player.experimental-es2021.js	902.7 KiB (286.6 KiB)	902.6 KiB (286.6 KiB)	+0.1 KiB
shaka-player.experimental.debug.js	1953.6 KiB (437.4 KiB)	1953.5 KiB (437.4 KiB)	+0.2 KiB
shaka-player.experimental.js	1027.4 KiB (319.9 KiB)	1027.2 KiB (319.9 KiB)	+0.1 KiB
shaka-player.hls-es2021.debug.js	950.3 KiB (236.0 KiB)	950.3 KiB (236.0 KiB)	+0.0 KiB
shaka-player.hls-es2021.js	490.4 KiB (165.7 KiB)	490.4 KiB (165.7 KiB)	+0.0 KiB
shaka-player.hls.debug.js	1153.0 KiB (266.9 KiB)	1153.0 KiB (266.9 KiB)	+0.0 KiB
shaka-player.hls.js	567.0 KiB (186.6 KiB)	567.0 KiB (186.6 KiB)	+0.0 KiB
shaka-player.ui-es2021.debug.js	1548.6 KiB (372.3 KiB)	1548.4 KiB (372.2 KiB)	+0.1 KiB
shaka-player.ui-es2021.js	868.2 KiB (276.7 KiB)	868.0 KiB (276.6 KiB)	+0.1 KiB
shaka-player.ui.debug.js	1852.1 KiB (418.2 KiB)	1851.9 KiB (418.1 KiB)	+0.2 KiB
shaka-player.ui.js	981.4 KiB (307.1 KiB)	981.2 KiB (307.1 KiB)	+0.1 KiB

[shaka-bot]

Incremental code coverage: 100.00%