Get transactions and mobile vitals trough the sentry api.

### Problem Statement

I was trying to find the a way how to get mobile vitals like cold/hot start, frozen frames and other transactions so I can pass them to our custom reporting tools. This does not seem to be possible at the moment. Is there any plan to add this?

### Solution Brainstorm

I would like to be able to download transactions and maybe even some mobile vitals overview for different environments for customizable time period.

### Product Area

Performance

Start by reviewing Sentry’s existing API capabilities for the Performance product area and how transactions and mobile vitals are represented. Done would mean a defined API approach for retrieving those metrics across environments and customizable time periods for external reporting.

Written by the indexing model from the issue text.