[PM-25949] ExternalCallback Integration tests for SSO Project (#6809)

* feat: add new integration test project

* test: add factory for SSO application; ExternalCallback integration tests.

* test: modified Integration tests to use seeded data instead of service substitutes with mocked responses, where possible.

* fix: re-organize projects in solution. SsoFactory now in its owning project with SSO integration test which match the integration test factory pattern more closely.

* claude: better naming of class fields.

test/IntegrationTestCommon/Factories/IdentityApplicationFactory.cs

@@ -189,7 +189,7 @@ public class IdentityApplicationFactory : WebApplicationFactoryBase<Startup>
     /// Registers a new user to the Identity Application Factory based on the RegisterFinishRequestModel
     /// </summary>
     /// <param name="requestModel">RegisterFinishRequestModel needed to seed data to the test user</param>
-    /// <param name="marketingEmails">optional parameter that is tracked during the inital steps of registration.</param>
+    /// <param name="marketingEmails">optional parameter that is tracked during the initial steps of registration.</param>
     /// <returns>returns the newly created user</returns>
     public async Task<User> RegisterNewIdentityFactoryUserAsync(
         RegisterFinishRequestModel requestModel,

test/IntegrationTestCommon/IntegrationTestCommon.csproj

@@ -3,12 +3,12 @@
   <PropertyGroup>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
-  
+
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.10" />
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="8.0.0" />
   </ItemGroup>
-    
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\Identity\Identity.csproj" />
     <ProjectReference Include="..\..\util\Migrator\Migrator.csproj" />