[#174005728,#174005947] All psp are filtered

[Undermaken]

Short description:
This PR fixes mainly a bug about psp list filtering:
if the retrieved psp has a language not compliant with which one used by the device the psp will be discarded.

Now the language used to retrieve and filter the psp is one of these used by the app: italian or english
If the current language is neither italian or english, en is the fallback

Another fix is about the current language representation. The following screen is on device where the device language is polish

[pagopa-github-bot]

Affected stories

• 🐞 #174005728: [major] La lista dei PSP deve essere filtrata per lingua italiano o inglese
• 🐞 #174005947: [trivial] Nelle preferenze se la lingua del dispositivo non è tra quelle supportate viene visualizzata la lingua del dispositivo invece di quelle supportate

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