Content Browser imrovements

[Gerbil789]

• [x] Use ImGui content browser functionality

Right click menu

• [x] Create folder
• [x] Delete folder/s
  • [x] Recursive if not empty
• [x] Create new assets
  • [x] Materials
  • [x] Scenes
• [x] Delete files
  • [x] ImGui delete stuff (update ui correctly)
• [x] Rename files
  • [x] Change id

  • [ ] Write new name

• [x] Search bar
• [x] Select items
• [ ] Update material panel
• [x] Multiselect items
• [ ] Drag & Drop files into content browser from outside
  • [ ] Images
  • [ ] set up for other file types

icons

• [x] Folder
• [x] Empty folder
• [x] File

problems

• [ ] Display long filenames on multiple lines
• [ ] Text should be inside selected item border
• [x] Created materials have invalid default textures
• [ ] Code cleanup