Add Copilot user-teams daily metrics report endpoints

[Tens1des]

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

Endpoints:

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

Docs: https://docs.github.com/en/rest/copilot/copilot-usage-metrics

[Tens1des]

I'll take this

[gmlewis]

Thank you, @Tens1des !