Use environment secrets for Crowdin actions

[Nateowami]

Zizmor has flagged our use of secrets outside an environment as not being a security best-practice, since it means the secrets are available to every action that runs. See https://docs.zizmor.sh/audits/#secrets-outside-env

Instead, secrets should be put in an environment (e.g. a "Crowdin" environment), and then workflows should state which environment they use.

What that means is that the security improvement isn't an update to a workflow; it's a change to how our secrets are stored in GitHub, to have better access control. However, doing that does necessitate an update to the workflows.

I've created a Crowdin environment in the repo settings, set CROWDIN_PROJECT_ID and CROWDIN_API_KEY, and updated the workflow to reference them. After this is merged the old secrets should be removed from the repo's main secrets, so they're only available via the environment.

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This change is 

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.31%. Comparing base (5b88991) to head (cc28415).
⚠️ Report is 1 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

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##           master    #3753   +/-   ##
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  Coverage   81.31%   81.31%           
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  Files         620      620           
  Lines       39080    39080           
  Branches     6371     6352   -19     
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  Hits        31778    31778           
- Misses       6317     6330   +13     
+ Partials      985      972   -13     

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[pmachapman]

@pmachapman reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Nateowami).