add more possible file types in attachments

[MrHertal]

Currently you can only attach images to the prompt along with a text.

Some providers are handling more file types. This is the case for Bedrock Converse API which accept documents like pdf, docx etc.

In this PR, I created an additional part type called file which is more generic than the current image part type.

I didn't want to break anything so I duplicated the existing mechanism of image without replacing it.
You can pass the file blob or a URL to the file, just like with the images.

For now I only updated Bedrock provider to handle this new part type. I wanted some feedbacks before working on the other providers.

[lgrammel]

Which provider did you use to try this out? Anthropic? are you sure that the contents of the PDF have been used?

[MrHertal]

Which provider did you use to try this out? Anthropic? are you sure that the contents of the PDF have been used?

Yes I tried with Bedrock and Claude 3. If you run the example:

$ pnpm tsx src/stream-text/amazon-bedrock-multimodal.ts
...
Overall, this document appears to be a standard Lorem Ipsum placeholder text, commonly used as a sample or filler text in design and publishing projects when the final content is not yet available.

it reads the pdf which is a Lorem ipsum