Allow disabling the onboarding panel from enterprise policies

[dannycolin]

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• I agree to license my code under the MPL 2.0 license.
• I rebased my work on top of the main branch.
• I ran npm test and all tests passed.
• I added test coverages if relevant.

Description

Allow disabling the onboarding panel from enterprise policies.

policies.json example:

{
  "policies": {
    "3rdparty": {
      "Extensions": {
        "@testpilot-containers": {
	  "disableOnboarding": true
	}
      }
    }
  }
}

Note: I didn't implement a policy to disable only the feature to connect to Mozilla VPN as requested because I prefer to do it in a separated patch.

Type of change

Select all that apply.

• Bug fix
• New feature
• Major change (fix or feature that would cause existing functionality to work differently than in the current version)

Tag issues related to this pull request:

• Disable onboarding from Firefox policies #2565

Additional information

cc'ing @mkaply for a review on this too.

[mkaply]

I don't think we need an error here. This is the normal case.

Does it actually throw if it isn't there?

[dannycolin]

It does. We have bug 1868153 to track it upstream.

[mkaply]

Let's not show the error though since nothing can be done.

[mkaply]

Let's not show the error though since nothing can be done.