many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/Infrastructure/BlobStorage/Contracts/CommonFileNames.cs

@@ -0,0 +1,7 @@
+namespace Hutopy.Infrastructure.BlobStorage.Contracts;
+
+public static class CommonFileNames
+{
+    public const string ProfilePicture = "profilePicture";
+    public const string BannerPicture = "bannerPicture";
+}