[#79] AppDbContext: Use compiled queries

Tests/UnitTests/HelperTests/EbicsTest.cs

@@ -33,7 +33,7 @@ namespace Tests.UnitTests.HelperTests {
                 DateString = "2021-01-31",
             };
             using var ctx = new AppDbContext();
-            var members = ctx.Members.ToList();
+            var members = await ctx.FetchMembers().ToListAsync();
             Assert.That(members, Has.Count.GreaterThan(0));
             using var exporter = new Ebics(v, FileName, version, mode);
             await exporter.ExportAsync(members.Select(m => new Transaction(m, 1234.56m, "EUR", m.MgNr % 100)));