Check remote API status

[ilicfilip]

Context

We ping our API for a lot of things, not just for registration and getting data but also getting badge graphics and etc.

We have fallback for images and we cache API response for 5 minutes if the response from our server was empty, but users don't know that which can be confusing.

This PR adds following:

• A note on the Settings page if the Page types are not loaded from API
• A button on the Settings page which pings our server and displays a status message (so user can check API status in the real time).
• Improves check for "Save settings" task, to add it only if Page types are fetched from our server

The thing that still needs to be implemented is some kind of notice, probably on the PP Dashboard page when it is detected that some API call has failed.

Fixes #422

[github-actions]

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[ilicfilip]

@tacoverdo , I have added everything we talked about in the meeting except the notice, on the PP Dashboard screen, that Page Types are not fetched from our server - we said that we might replace the content of the Challenge widget with it.

The reason is that if our API is not working a lot of things will not work, including the Onboard process. Then again, if some data is fetched from our API, for example Challenge content - do we want to replace it with the notice?

Since there is an info about the Page Types not being loaded from our server (and the button for testing API status) on the Settings page maybe that is enough for now?

This is the note which is displayed to the user if pages are not loaded:
There seems to be a problem with loading page types from our server. Please try again later or check the API status.