[ChannelNewsAsia] Add new extractor

[fourjr]

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Extractor to download videos from Singapore news site https://www.channelnewsasia.com

[dstftw]

Read coding conventions.

[fourjr]

I have updated the code to follow the conventions.

[cypheron]

I guess because of the huge backlog @dstftw doesn't actually check any code, he writes that "read the conventions" nonsense over all PR's without ever mentioning a specific thing. Hope that @dstftw can get off his horse and does some work, otherwise I don't know if my excitement about ytdl being back was really appropriate.