Add Secrets to the admin page

[boardend]

Secrets list view:

---

Adding a new secret:

• Name, Type, Value and Project can be specified
  • Created by will be set to the current user

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Modifying an existing secret:

• Value is not presented to the user
• Everything is read only
  • Except that the Value can be overwritten
    • TextInput or Textarea based on Type

[duke-nyuki]

Task linked: QF-3734 Add a way to configure secrets via the Admin

[boardend]

@suricactus BadSignature error occurs when you have secrets in the db encrypted with a different key (e.g. a db dump from another system). Try to clean the secrets table and test with newly created secrets.

[boardend]

There is now a read-only ProjectSecretInline:

The only missing part is a button in the project admin to create a new secret for that project. @suricactus do you have an idea how this can be implemented (without a custom project template)?

Otherwise I think this is ready to be merged.

[suricactus]

The only missing part is a button in the project admin to create a new secret for that project. @suricactus do you have an idea how this can be implemented (without a custom project template)?

See potential fix to this issue here: https://github.com/opengisch/qfieldcloud/pull/949

Otherwise I think this is ready to be merged.

I did a small commit, check it's commit and message. In general, we always prefer to use the decorator for new admin stuff, the old way looks a bit too hacky.

[boardend]

One thing which you might have considered is to move the validation from admin.ProjectSecretForm.clean() to the models.Secret.clean().

Since we are messing with the name in admin.ProjectSecretForm.clean() too, I will leave everything in one place. But I will keep it in mind, when we e.g. extend the scope of the secrets.

Just re-based on my machine. If the tests pass, I will squash and merge.