Change Requests accepted metric API

> [!Note]
> This issue was ported from https://github.com/augurlabs/augur/issues/2627 because it relates to a contribution that was deemed to still be useful.

The canonical definition is here: https://chaoss.community/?p=3589

Start with the canonical definition linked in the issue and review the ported Augur issue for context. Identify the relevant API entry point and the expected representation of the Change Requests accepted metric; done means the metric is exposed according to the canonical definition and its behavior is covered by project tests.

Written by the indexing model from the issue text.