Chat: selected model is not picked up when request goes through core proxy early on

[bpasero]

Steps to Reproduce:

1. select a non-default model in chat
2. reload window
3. very quickly send a message

=> 🐛 the model used is the default one

[bpasero]

@roblourens I am going ahead and stop sending the selected model here (userSelectedModelId):

vscode/src/vs/workbench/contrib/chat/browser/chatSetup.ts

Lines 353 to 357 in 4bd54e5

	await chatService.resendRequest(requestModel, {
	...widget?.getModeRequestOptions(),
	modeInfo,
	userSelectedModelId: languageModel,
	});

Because it was undefined right on startup anyway. The issue still reproduces though, even though the current language model is correctly set right before we resend the request (via widget?.input.currentLanguageModel), so maybe something is racing within the chat model?