This should be implemented similar to Model Engine's mcmeta Blockbench plugin.

Essentially, it adds two actions when right-clicking a texture:

• Edit MCMETA
• Import MCMETA

Edit MCMETA opens the window below, allowing you to modify the content, while Import MCMETA loads the selected MCMETA file’s content into the input field of the edit window.

Additionally, I would enhance this by:

• Adding MCMETA JSON validation (See format here)
• Restricting these two new actions to animated textures, ensuring they aren’t available for normal textures