Add Swift SDK generation and release checks

[TimurBaiguskarovAspose]

Summary

• Add Swift SDK generation for Aspose.BarCode Cloud API v4.0.
• Add the Swift SDK submodule backed by Aspose.BarCode-Cloud-SDK-for-Swift.
• Add Swift package runtime helpers for OAuth client credentials/access token configuration.
• Add Swift request-shape tests, live integration smoke tests, example app, README, CHANGELOG, and release docs.
• Add codegen PR checks for Swift generation reproducibility, Swift tests, and live API smoke tests.

Validation

• make swift
• swift test
• make integration-test
• ./scripts/check_all_urls.sh

Release Notes

• First Swift SDK release will be tagged as v26.4.0.
• SwiftPM users should depend on version 26.4.0.