Configure `AddUserSecrets` by default in dev environment

[liliankasem]

Issue describing the changes in this PR

resolves #2661

Pull request checklist

• [x] My changes do not require documentation changes
  • [ ] Otherwise: Documentation issue linked to PR
• [ ] My changes should not be added to the release notes for the next release
  • [x] Otherwise: I've added my notes to release_notes.md
• [x] My changes do not need to be backported to a previous version
  • [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x] I have added all required tests (Unit tests, E2E tests)

Additional information

UserSecrets are now added by default. when the environment is 'Development'. This changesfollows the same pattern as WebApplicationBuilder, but we need to use EntryAssembly instead.

Q: Do we also want to load in appsettings by default similar to WebApplicationBuilder?

        configuration.AddJsonFile("appsettings.json", optional: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);