Add ShadowShell plugin to plugin_packages.json

[hahwul]

I am submitting a new Plugin Package

Repository URL

https://github.com/hahwul/ShadowShell

Release Checklist

• I have tested the plugin on
  • Windows
  • macOS
  • Linux
• My GitHub release contains all required files
  • plugin_package.zip
  • plugin_package.zip.sig
• Release immutability is enabled
• GitHub Tag name matches the version number specified in my caido.config.json
• The id in my caido.config.json matches the id in the plugin_packages.json file.
• My README.md describes the plugin package purpose and provides clear usage instructions.
• I have read the developer policy at https://developer.caido.io/policy.html, and have assessed my plugin package adherence to this policy.
• I have added a license in the LICENSE file and it matches the license field in the plugin_packages.json file.
• My project respects and is compatible with the original license of any third-party code that I'm using.
  I have given proper attribution to these other projects in my README.md and/or LICENSE.