feat: generic attachment filetype: drag n drop, opening

[neo451]

• Idea and logic from https://github.com/hakonharnes/img-clip.nvim
• Allow all file formats that the obsidian app supports to be dropable.

TODO:

• Drag n drop
• Follow path
• Cleanup logic.
• Tests
• Reflect in README/Wiki, including the limitations of different terminals, link to https://github.com/hakonharnes/img-clip.nvim?tab=readme-ov-file#%EF%B8%8F-drag-and-drop

[sotte]

This is a nice feature!