api: Webhooks for VOD

[victorges]

What does this pull request do? Explain your changes. (required)

This implements a couple of webhooks for the VOD feature in general, as
per this short discussion/spec.

Specific updates (required)

• New event types for webhooks
• Webhooks for tasks
• Webhooks for assets

-

• How did you test each of these updates (required)
  yarn test (might write some explicit tests for these, idk)

Does this pull request close any open issues?
Implements #1005

Checklist:

• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[vercel]

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Name	Status	Preview	Updated
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[codecov]

Codecov Report

Merging #1099 (b61fe67) into master (0de08c9) will increase coverage by 0.20327%.
The diff coverage is 75.67568%.

❗ Current head b61fe67 differs from pull request most recent head 743649c. Consider uploading reports for the commit 743649c to get more accurate results

@@                 Coverage Diff                 @@
##              master       #1099         +/-   ##
===================================================
+ Coverage   50.21750%   50.42077%   +0.20326%     
===================================================
  Files             66          66                 
  Lines           4138        4159         +21     
  Branches         730         733          +3     
===================================================
+ Hits            2078        2097         +19     
- Misses          1814        1815          +1     
- Partials         246         247          +1     

Impacted Files	Coverage Δ
packages/api/src/controllers/task.ts	13.26531% <0.00000%> (ø)
packages/api/src/webhooks/cannon.ts	47.95322% <0.00000%> (ø)
packages/api/src/controllers/asset.ts	46.49123% <75.00000%> (+0.71345%)	⬆️
packages/api/src/task/scheduler.ts	51.80723% <81.48148%> (+10.26876%)	⬆️

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[victorges]

PR description that Github is not showing:

[victorges]

Aha! The PR template apparently came with a big comment that wasn't closed, then everything was hidden lol

Fixed now

[figintern]

Webhook logic LGTM, just some nits