Send documents to the LLM if it supports it

[l3ochan]

Describe the feature you'd like to request

Being able to send documents and pictures through the "Chat with AI" box would be useful, the Nextcloud assistant app already supports sending files to the LLM in other windows like the "Generate Text" one.
The user would click on an icon that would give them the option to select file that are stored on their accounts on the current NC instance or upload the files directly from their computer. They would also be able to send a text prompt along with their file(s).

Describe the solution you'd like

A button to be able to select file that are stored inside the current NC instance or to be able to upload files from the user's computer.

Describe alternatives you've considered

None, it's an enhancement for the Nextcloud Assistant's interface.