Moving/renaming folder

Do operations with assets outside of Unity is not recomended, instead, using the class AssetDatabase, and ofcourse, you can do custom inspector/editor tools to improve the management of all kind assets (folders, animatior controllers, materials etc...). Look to AssetDatabase class, and see some classes to build editor tools: Editor Window, GUILayout, EditorGUILayout.

Look at this example script, he creates a window and list all folders of your project:

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEditor;
 using UnityEngine;
 
 public class FoldersListWindow : EditorWindow
 {
     private List<Folder> assetsFolders = new List<Folder>();
     private Vector2 foldersListScroll;
 
     [MenuItem("Window/FolderList %#o")]
     private static void Init()
     {
         FoldersListWindow window = GetWindow<FoldersListWindow>();
         window.titleContent = new GUIContent { text = "Folder List" };
         window.Show();
     }
 
     private void OnEnable()
     {
         foreach (string folder in AssetDatabase.GetSubFolders("Assets"))
         {
             assetsFolders.Add(new Folder(folder));
         }
     }
 
     private void OnGUI()
     {
         GUILayout.BeginArea(new Rect(1f, 1f, Screen.width / 3f, Screen.height), GUI.skin.box);
         foldersListScroll = EditorGUILayout.BeginScrollView(foldersListScroll, true, true);
 
         DrawFolders(assetsFolders);
 
         EditorGUILayout.EndScrollView();
         GUILayout.EndArea();
     }
 
     private void DrawFolders(List<Folder> foldersList)
     {
         for (int i = 0; i < foldersList.Count; i++)
         {
             EditorGUILayout.BeginVertical(GUILayout.Width(Screen.width / 3f));
 
             foldersList[i].isFoldoutShown = EditorGUILayout.Foldout(foldersList[i].isFoldoutShown, foldersList[i].folderName);
 
             if (foldersList[i].haveSubFolders && foldersList[i].isFoldoutShown)
             {
                 EditorGUI.indentLevel++;
 
                 DrawFolders(foldersList[i].subFolders);
 
                 EditorGUI.indentLevel--;
             }
 
             EditorGUILayout.EndVertical();
         }
     }
 }
 
 // THIS CLASS IS USED TO REPRESENT A FOLDER (WITH SUB FOLDERS) IN THE ASSETS FOLDER
 public class Folder
 {
     public string fullPath;
     public string folderName;
     public bool haveSubFolders;
     public bool isFoldoutShown;
     public int subFoldersCount;
     public List<Folder> subFolders;
 
     public Folder(string path)
     {
         fullPath = path;
         folderName = GetOnlyFolderName(fullPath);
         haveSubFolders = CheckForSubFolders(fullPath);
 
         if (haveSubFolders)
         {
             subFolders = new List<Folder>();
             string[] folders = AssetDatabase.GetSubFolders(fullPath);
 
             foreach (string item in folders)
             {
                 subFolders.Add(new Folder(item));
             }
 
             subFoldersCount = subFolders.Count;
             isFoldoutShown = true;        
         }
         else
         {
             haveSubFolders = false;
             subFoldersCount = 0;
             isFoldoutShown = false;
         }
     }
 
     private bool CheckForSubFolders(string path)
     {
         string[] folders = AssetDatabase.GetSubFolders(path);
         if (folders.Length > 0)
             return true;
         else
             return false;
     }
 
     private string GetOnlyFolderName(string path)
     {
         return path.Substring(path.LastIndexOf('/') + 1);
     }
 }

Really a bit "complicated", but it gives you the power of manipulate all assets in a project.

I suggest to try KrojamSoft BatchRename