Added EF and DB to the core, crude demo in the UI

WinWARP.Core/Services/Interfaces/ILocalizationService.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace WinWARP.Core.Services.Interfaces;
+
+public interface ILocalizationService
+{
+    IEnumerable<string> GetSupportedLanguages();
+    string GetCurrentLanguage();
+    Task SetLanguageAsync(string languageCode);
+    string GetString(string resourceKey);
+}

WinWARP.Core/Services/Interfaces/INavigationService.cs

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+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Text;
+
+namespace WinWARP.Core.Services.Interfaces;
+
+public interface INavigationService
+{
+    void NavigateTo<TViewModel>(object parameter = null) where TViewModel : class;
+    void GoBack();
+    bool CanGoBack
+    {
+        get;
+    }
+    Type CurrentViewModelType { get; }
+    event EventHandler<Type> NavigatedToViewModel;
+}

WinWARP.Core/Services/Interfaces/ISubscriptionDbService.cs

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+using System;
+using System.Collections.Generic;
+using System.Text;
+using WinWARP.Core.Models.Entities;
+
+namespace WinWARP.Core.Services.Interfaces;
+
+public interface ISubscriptionDbService
+{
+    public Task<List<Subscription>> GetSubscriptionsAsync();
+    public Task AddSubscriptionAsync(Subscription subscription);
+}