Limit the number of selectable options in multi-choice survey questions

Description: Add an option to multi-choice (multiple selection) survey questions that allows admins to set a maximum number of answers a respondent can select (e.g. "choose up to 2"). Problem: Currently, multi-choice questions allow respondents to select as many options as they want. There is no way to cap the number of selections, which makes it impossible to force prioritization or gather more meaningful, constrained responses. Benefit: By setting a max-selection limit, survey creators can collect higher-quality, more deliberate answers — for example, asking users to pick their top 2 priorities from a list. This adds flexibility to the survey builder without changing the existing behavior for those who don't need it.