REQ: Detect references to drop files in chat the way references to files to add are detected and prompted

[5ocworkshop]

Issue

Right now aider will notice if you refer to files in a certain way in the chat and prompt you if you want to add them to the chat if they are not already present. This is really helpful.

Likewise, I think it would be good if there was an explicit reference to dropping files from the chat, that they could be similarly prompted for confirmation with the user.

The reason this is desirable is because it allows the writing of prompts that can make decisions about adding and removing files from the chat that can have additional prompting instructions in them. For example, you could have a small control prompt that looks at the error/debugging situation and based on what it wants to do next, it could unload one extended prompt file and load a different one. This would make it easier to have multi-path prompting without having to manually make these decisions and changes every time.

Version and model info

Aider v0.59.1
Main model: claude-3-5-sonnet-20240620 with diff edit format, prompt cache, infinite output
Weak model: claude-3-haiku-20240307