[cpac] Add new extractor

[ealgase]

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What is the purpose of your pull request?

• Bug fix
• Improvement
• New extractor
• New feature

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Description of your pull request and other information

This adds an extractor for cpac.ca, closing #18148. Livestreams still need to be supported, as well as multiple languages for videos.

[dstftw]

1. This should use _search_json_ld.
2. This should be done in generic extractor.
3. _search_json_ld should be extended to be able to process all JSON-LD entries when expected_type is specified.