Disable Package Manager Notifications

[mrixner]

• I have read the contributing guidelines, and I agree with the Code of Conduct.
• Have you checked that there aren't other open pull requests for the same changes?
• Have you tested that the committed code can be executed without errors?
• This PR is not composed of garbage changes used to farm GitHub activity to enter potential Crypto AirDrops.
  Any user suspected of farming GitHub activity with crypto purposes will get banned. Submitting broken code wastes the contributors' time, who have to spend their free time reviewing, fixing, and testing code that does not even compile breaks other features, or does not introduce any useful changes. I appreciate your understanding.

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This PR allows the user to disable notifications for when updates are available from certain package managers. If updates are available from other package managers, those will still be shown. The updateable packages count reflects all managers, however the list of available updates in the notification only includes those without notifications disabled.

It also updates the CheckboxCard setting to allow it to use the complex settings, and it ports the AlwaysElevate and (removed) AllowParallelInstalls... settings to use those complex settings. AlwaysElevate settings will be transferred on open, AllowParallelInstalls... will not be as it is disabled in the code anyway.

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Closes #3319

[Martí Climent (marticliment)]

and (removed) AllowParallelInstalls...

Why port it if it has been removed?

[mrixner]

and (removed) AllowParallelInstalls...

Why port it if it has been removed?

Because while the checkbox was removed from the UI, the code for it is still present, just commented out, so I didn't know if you had plans to add it back at some point and migrated it just in case.

[Martí Climent (marticliment)]

and (removed) AllowParallelInstalls...

Why port it if it has been removed?

Because while the checkbox was removed from the UI, the code for it is still present, just commented out, so I didn't know if you had plans to add it back at some point and migrated it just in case.

I removed the code when redesigning operations, only the checkbox remains (which I forgot to remove)

[mrixner]

OK, I'll go remove that stuff then. I had just now noticed there was no longer any implementation details (and I wasn't transferring the settings anyway).