feat: prepare Pro licensing and Android API 36

Services/IPlayBillingService.cs

@@ -0,0 +1,24 @@
+namespace LMEMappeCatastaliApp.Services;
+
+public interface IPlayBillingService
+{
+    Task<PlayBillingResult> RestoreAsync(CancellationToken cancellationToken = default);
+    Task<PlayBillingResult> PurchaseAsync(string basePlanId, CancellationToken cancellationToken = default);
+}
+
+public sealed record PlayBillingResult(bool Completed, bool HasActiveSubscription, bool UserCancelled, string Message)
+{
+    public static PlayBillingResult Active(string message) => new(true, true, false, message);
+    public static PlayBillingResult Base(string message) => new(true, false, false, message);
+    public static PlayBillingResult Cancelled(string message) => new(false, false, true, message);
+    public static PlayBillingResult Failed(string message) => new(false, false, false, message);
+}
+
+public sealed class UnavailablePlayBillingService : IPlayBillingService
+{
+    public Task<PlayBillingResult> RestoreAsync(CancellationToken cancellationToken = default) =>
+        Task.FromResult(PlayBillingResult.Failed("Google Play Billing è disponibile solo nell'app Android installata da Google Play."));
+
+    public Task<PlayBillingResult> PurchaseAsync(string basePlanId, CancellationToken cancellationToken = default) =>
+        Task.FromResult(PlayBillingResult.Failed("Google Play Billing è disponibile solo nell'app Android installata da Google Play."));
+}