User Feedback integration

[armcknight]

Description

Create the high level integration API to inject a widget that will present a modal form to capture end user feedback.

[armcknight]

We'll offer a variety of ways for the form to be presented.

options:

• widget (User Feedback UI widget #4270)
• a shake gesture
• a UIGestureRecognizer they create and hand to us (and maybe offer a couple pre-packaged gestures like other bug reporters offer out of the box)
• triggering from a button they create and offer for us to inject the action
• manually calling a method to display (in SentrySDK.h)

They will also be able to use a fully custom method to gather the required data and simply call a method like we already have today with SentrySDK.captureUserFeedback to submit the envelope.

[armcknight]

To update on the above comment after going through the review process in the linked PR, we decided to not accept a custom gesture recognizer in the API for now.