feat(api): manage localized push template definitions

Add revision-protected reads, atomic upsert and deletion with structured actions. Preserve omitted translations and fix insertion of new push languages.

Ref: IT-1627

HrynCo.NotificationService.Web/Controllers/Api/Services/PushTemplateTranslationRequest.cs

@@ -0,0 +1,11 @@
+using HrynCo.NotificationService.DAL.Abstract.Templates;
+
+namespace HrynCo.NotificationService.Web.Controllers.Api.Services;
+
+public sealed class PushTemplateTranslationRequest
+{
+    public required string LanguageCode { get; init; }
+    public required string Title { get; init; }
+    public required string Body { get; init; }
+    public PushTemplateActions Actions { get; init; } = new();
+}