🐛 [ui] improve errors on macOS with missing network client entitlements

[Ehesp]

Reported on macOS, Sign In is causing problems:

Checklist

• Google Sign In produces a blank screen when signing in:

• Signing in with email produces a network error - this was fixed by enabling entitlements - this should be documented or a better error thown.

[bazookon]

You must enable "Outgoing connections" in xcode

[Ehesp]

Thanks, will get it added to the docs.

[lesnitsky]

@bazookon's suggestion would work, however it is recommended to edit entitlements manually.

To enable outgoing requests, add the following lines to the DebugProfile.entitlements and Release.entitlements:

<key>com.apple.security.network.client</key>
<true/>

[orangeandclementine]

Thank you @darshankawar for referencing me to this issue. May I recommend in the meantime that we add a line to the documentation referencing that the flag may need to be changed? (as mentioned in #8863). Otherwise I do not think the documentation is complete.

I'll just re-affirm that I struggled for like a week on this issue and almost gave up. Would hate for a less experienced dev to just abandon ship.

If you tell me how to update documentation, I will do so.