GroupBy on more properties in Release health session statistics API

[Angelodaniel]

Problem Statement

API: https://docs.sentry.io/api/releases/retrieve-release-health-session-statistics/

As a developer I only have a small list of properties to group on
"The available groupBy conditions are project, release, environment and session.status."

I want to group the data in a way that it would make more sense for my 3th party apps I feed data to.

Solution Brainstorm

Being able to use custom properties in the GroupBy input so we can format the data in a better way.

┆Issue is synchronized with this Jira Improvement by Unito

[getsantry]

Assigning to @getsentry/support for routing, due by Tuesday, March 21st at 11:30 (yyz). ⏲️

[kooskoos20]

Grouping release health statistics based on location would be a great use case for this. It will help to see the distribution geographically.