Add function to capture user feedback

[bruno-garcia]

Other Sentry SDKs have a function called captureUserFeedback that takes an event_id, and user input such as name, email and comments. develop docs on it are here: https://develop.sentry.dev/sdk/features/#user-feedback

A new feedback format was added recently to power the Web Widget (see: https://docs.sentry.io/product/user-feedback/).
In JS the function name became captureFeedback. Final docs are not yet on develop but tracked here:

• SDK docs for User Feedback v2 develop#1206