[FEATURE] Support drag-and-drop to load .nam models

[walking]

Is your feature request related to a problem? Please describe.
In the plugin, the only way to load a model is to use the OS's built-in file selector. However, the location it initially shows seem to reset occasionally. I have to navigate all the way to the folder where I store my *.nam models again whenever this happens.

Describe the solution you'd like
Allow dragging and dropping *.nam models directly onto the plugin, e.g. from a file explorer or the DAW's sample browser.

Most DAWs like FL Studio or Reaper have a built in sample/file explorer and allow you to add 'favourite' folders. It's much easier to browse for .nam models there rather than the OS's built-in file selector, so I would like to suggest allowing dragging directly from an outside source to the plugin.

Describe alternatives you've considered
N/A

Additional context
N/A