feat(explorer): add explorer_add_cwd action

[lucasrabiec]

• Added a new action explorer_add_cwd that allows users to add files or directories in the current working directory instead of selected directory (accessible via the A keybinding in explorer mode).
• Refactored the file/directory creation logic by introducing a shared helper function explorer_add_to, used by both explorer_add and the new explorer_add_cwd actions.