Add directory listing option for project plugin

I have always wanted the project file listing to have the option of showing all files, including those untracked by the VCS. I often have to use the project terminal in Kate to open files that I need to edit but are not tracked by version control.

This adds a "Directory Listing" configuration option that allows switching autoloaded repository projects from VCS-only file listing to full directory scanning. A separate "Show hidden files" option controls whether dotfiles are included. Both settings persist across sessions and trigger a live reload of affected projects when toggled, so users can configure Kate to always show the full directory listing with or without hidden files depending on their preference.