Add an API for User Feedback

[renchap]

Problem Statement

Currently collecting User Feedback requires either:

• Loading the feedback modal from Sentry, without many customisation available
• Implementing it from scratch, including an API call to Sentry

This does not easily allow to create a custom feedback form.

Solution Brainstorm

Similar to the way it has been implemented in @sentry/react-native , I would like a [captureFeedback](https://github.com/getsentry/sentry-react-native/blob/ab6a1fe411f33dbfc676a2d81a3694ca56366f05/src/js/sdk.tsx#L244) function in @sentry/browser.

It could probably re-use most of the code from the RN implementation, which could be moved into this package to avoid duplication.

[AbhiPrasad]

Hey, thanks for writing in! This sounds like a great idea. PRs are welcome for those who would like to help, otherwise backlogging this for now.

If anyone else would like this, please react to this issue and leave a comment - helps us understand priority.

[tetsuwanadam]

I would also really like to see this. I'm finding implementing user feedback via the API a bit difficult, and it would be nice to not need to create a project:write auth token.

[AbhiPrasad]

getsentry/sentry-react-native#2486