Updated DependencyInjection.cs to change ISmsSender and
IEnvelopeSmsHandler lifetimes from Singleton to Scoped,
ensuring per-request instantiation. Added Microsoft.Extensions.Http
package to EnvelopeGenerator.Server.Client.csproj for enhanced
HttpClient handling. Refactored AnnotationService, AuthService,
DocumentService, EnvelopeReceiverService, SignatureCacheService,
and SignatureService to use IHttpClientFactory, improving
flexibility and testability. Introduced a named HttpClient
"EnvelopeGenerator.Server" in Program.cs for internal API calls,
and removed the previous HttpClient setup using HttpContextAccessor.
Added necessary using directives for System.Net.Http across
service files to support these changes.
Replaced "EnvelopeGenerator.WebUI" with "EnvelopeGenerator.Server" and "EnvelopeGenerator.WebUI.Client" with "EnvelopeGenerator.Server.Client". Updated project entries, solution configuration platforms, and nested projects to reflect these changes.
