Migrate the SimplePlugins file-management feature into the YAMA client as an
experimental feature. The migrated CFileManager, MasterEncoder and Info-Zip
sources live under client/file/ and are isolated in the SimplePluginsFile
namespace to avoid clashing with the native FileManager class.
Add COMMAND_FILE_MANAGER_PLUGIN (163) and LoopFileManagerPlugin, spawned as
a sub-connection from KernelManager. Add an "实验功能" submenu with a
"文件管理" entry above "客户管理" in the online-hosts right-click menu,
routed via OnExperimentFileManager to the existing TOKEN_DRIVE_LIST_PLUGIN
dialog path.
Co-Authored-By: deepseek-v4-pro
