Add Copilot repository daily metrics report endpoints

[Tens1des]

The Copilot usage metrics API exposes repos-1-day reports for enterprises and organizations, but go-github does not model them yet.

Endpoints:

• GET /enterprises/{enterprise}/copilot/metrics/reports/repos-1-day
• GET /orgs/{org}/copilot/metrics/reports/repos-1-day

Docs:

• https://docs.github.com/en/rest/copilot/copilot-usage-metrics
• https://docs.github.com/en/copilot/reference/copilot-usage-metrics/copilot-usage-metrics#repository-level-fields-api-only

Also missing on pull_requests: copilot_suggestions_by_comment_type.

[Tens1des]

I'll take this

[gmlewis]

Thank you, @Tens1des!