Make question type required in `AskUser` tool

[jerop]

Today, it's optional then defaults to Choice -

gemini-cli/packages/core/src/confirmation-bus/types.ts

Line 151 in 099aa96

type?: QuestionType;

Remember to update telemetry in https://github.com/google-gemini/gemini-cli/blob/main/packages/core/src/tools/ask-user.ts when this change is made

Originally posted by @jerop in #18820