Why not have mimeType and base64 array be part of top level interface

[lramos15]

Testing #244511

Using value just to have a simple constructor leads to some nasty type checking / type guarding. It would be better just to put the properties on the top level interface unless there's a good reason not to.

[justschen]

initially wanted to align with what open ai does:

export interface UserChatMessage {
    role: ChatRole.User;
    /**
     * The content of the chat message.
     */
    content: string | Array<ChatCompletionContentPart>;
    /**
     * An optional name for the participant. Provides the model information to differentiate between participants of the same role.
     */
    name?: string;
}
export type ChatCompletionContentPart = ChatCompletionContentPartImage | ChatCompletionContentPartText;
export interface ChatCompletionContentPartImage {
    image_url: ChatCompletionContentPartImage.ImageURL;
    /**
     * The type of the content part.
     */
    type: 'image_url';
}

with what we do here

vscode/src/vs/workbench/contrib/chat/common/languageModels.ts

Lines 28 to 48 in 45c88a5

	export interface IChatMessageTextPart {
	type: 'text';
	value: string;
	}
	export interface IChatMessageImagePart {
	type: 'image_url';
	value: IChatImageURLPart;
	}
	export interface IChatImageURLPart {
	/**
	* The image's MIME type (e.g., "image/png", "image/jpeg").
	*/
	mimeType: string;
	/**
	* The raw binary data of the image, encoded as a Uint8Array. Note: do not use base64 encoding. Maximum image size is 5MB.
	*/
	data: VSBuffer;
	}

but it couuuuld theoretically be top level yeah