Feature: add custom marshaller for env vars to hide them in the UI

[thielepaul]

I am using cheek to trigger regular backups with restic and need to pass the credentials as environment variables. These credentials should remain on the device and should not be accessible via the API or be displayed in the UI. Thus, I introduced a custom marshaller that replaces them with "***"

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.43%. Comparing base (67eab8f) to head (d3d8cfc).
Report is 93 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #230      +/-   ##
==========================================
- Coverage   74.34%   65.43%   -8.91%     
==========================================
  Files           5        6       +1     
  Lines         569      758     +189     
==========================================
+ Hits          423      496      +73     
- Misses        107      210     +103     
- Partials       39       52      +13     

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[bart6114]

Thanks for the PR @thielepaul.

Do you see any good use cases to have env vars be visible in the UI? In other words, what if we just use your secret marshalling technique on all the env vars? 🤔 This would negate the need for a specific secret_env field.

[thielepaul]

Yes, I do agree, there should be no need to see their values in the UI and I always prefer to keep it simple if possible

[bart6114]

Thanks for the contrib ❤️