Added accepted change requests count metric

[MoralCode]

Note

This PR was ported from augurlabs/augur#3532 filed by @Khusi2005 because the contribution was deemed to still be useful.

Added an implementation for the "Accepted Change Requests" metric based on the CHAOSS definition.The metric aligns with existing PR metrics and supports filtering by time period, repository, submitter, and merger.

Description

• Implements a new registered metric that counts accepted (merged) pull requests using Augur’s ingested GitHub data.
• Supports optional filters for date range, repository, repository group, PR submitter, and PR merger.
• Follows existing query patterns used in pull_request.py to ensure consistency with current metrics.
  This PR fixes Change Requests accepted metric API #477

Notes for Reviewers

• This change has been tested locally.
• Feedback and suggestions are welcome.

Signed commits

• Yes, I signed my commits.

AI Disclosure Warning: This PR description draft was generated using ChatGPT.

[MoralCode]

Porting mainly because @shlokgilda gave it a positive review previously.

This will need to be reviewed in depth to account for the new project name (CollectOSS). I noticed when porting that one of the database tables this depends on contained the augur name, and thus will break (as that column has been, or soon will be, renamed).