[BE, UI] Support to upload files as Taxonomy Term meta

[NuwanJ]

• The file is to be saved in the taxonomies folder with the timestamp as the file name.
  • Only support images (jpg, jpeg, png, SVG) and PDF files. All others should be avoided strictly
• The property saved in the metadata is that timestamp with the extension.
• At the UI level, the images should make a preview (max size: 120x120px), and for the PDFs, use the below image:

• At the API level, the full path should be returned