feat(marketing-initiated-premium): (Auth) [PM-27540] Add optional Marketing Property to RegisterSendVerificationEmailRequestModel (#6598)

Adds an optional `FromMarketing` property to the RegisterSendVerificationEmailRequestModel.

src/Core/Auth/Attributes/MarketingInitiativeValidationAttribute.cs

@@ -0,0 +1,29 @@
+using System.ComponentModel.DataAnnotations;
+using Bit.Core.Auth.Models.Api.Request.Accounts;
+
+namespace Bit.Core.Auth.Attributes;
+
+public class MarketingInitiativeValidationAttribute : ValidationAttribute
+{
+    private static readonly string[] _acceptedValues = [MarketingInitiativeConstants.Premium];
+
+    public MarketingInitiativeValidationAttribute()
+    {
+        ErrorMessage = $"Marketing initiative type must be one of: {string.Join(", ", _acceptedValues)}";
+    }
+
+    public override bool IsValid(object? value)
+    {
+        if (value == null)
+        {
+            return true;
+        }
+
+        if (value is not string str)
+        {
+            return false;
+        }
+
+        return _acceptedValues.Contains(str);
+    }
+}

src/Core/Auth/Models/Api/Request/Accounts/MarketingInitiativeConstants.cs

@@ -0,0 +1,10 @@
+namespace Bit.Core.Auth.Models.Api.Request.Accounts;
+
+public static class MarketingInitiativeConstants
+{
+    /// <summary>
+    /// Indicates that the user began the registration process on a marketing page designed
+    /// to streamline users who intend to setup a premium subscription after registration.
+    /// </summary>
+    public const string Premium = "premium";
+}

src/Core/Auth/Models/Api/Request/Accounts/RegisterSendVerificationEmailRequestModel.cs

@@ -1,5 +1,6 @@
 #nullable enable
 using System.ComponentModel.DataAnnotations;
+using Bit.Core.Auth.Attributes;
 using Bit.Core.Utilities;
 
 namespace Bit.Core.Auth.Models.Api.Request.Accounts;
@@ -11,4 +12,6 @@ public class RegisterSendVerificationEmailRequestModel
     [StringLength(256)]
     public required string Email { get; set; }
     public bool ReceiveMarketingEmails { get; set; }
+    [MarketingInitiativeValidation]
+    public string? FromMarketing { get; set; }
 }