feat: remove GHES 3.9, new action runner groups endpoints, new code s…

…canning alerts autofix endpoints, new sub-issues endpoints, new private registries enpoints, new code security endpoints, various description updates (#445)

BREAKING CHANGE: remove GHES 3.9
- Description updates
- New `/enterprises/{enterprise}/copilot/billing/seats`
- New `/enterprises/{enterprise}/settings/billing/cost-centers`
- New `/enterprises/{enterprise}/settings/billing/usage`
- New `/enterprises/{enterprise}/code-security/configurations/defaults`
- New `/enterprises/{enterprise}/code-security/configurations/{configuration_id}`
- New `/enterprises/{enterprise}/code-security/configurations/{configuration_id}/attach`
- New `/orgs/{org}/actions/runner-groups`
- New `/orgs/{org}/actions/runner-groups/{runner_group_id}`
- New `/orgs/{org}/actions/runner-groups/{runner_group_id}/repositories`
- New `/orgs/{org}/actions/runner-groups/{runner_group_id}/repositories/{repository_id}`
- New `/orgs/{org}/actions/runner-groups/{runner_group_id}/runners`
- New `/orgs/{org}/actions/runner-groups/{runner_group_id}/runners/{runner_id}`
- New `/orgs/{org}/copilot/metrics`
- New `/orgs/{org}/insights/api/route-stats/{actor_type}/{actor_id}`
- New `/orgs/{org}/insights/api/subject-stats`
- New `/orgs/{org}/insights/api/summary-stats`
- New `/orgs/{org}/insights/api/summary-stats/users/{user_id}`
- New `/orgs/{org}/insights/api/summary-stats/{actor_type}/{actor_id}`
- New `/orgs/{org}/insights/api/time-stats`
- New `/orgs/{org}/insights/api/time-stats/users/{user_id}`
- New `/orgs/{org}/insights/api/time-stats/{actor_type}/{actor_id}`
- New `/orgs/{org}/insights/api/user-stats/{user_id}`
- New `/orgs/{org}/private-registries`
- New `/orgs/{org}/private-registries/public-key`
- New `/orgs/{org}/private-registries/{secret_name}`
- New `/orgs/{org}/team/{team_slug}/copilot/metrics`
- New `/orgs/{org}/team/{team_slug}/copilot/usage`
- **Deprecate `/orgs/{org}/{security_product}/{enablement}`**
- New `/repos/{owner}/{repo}/code-scanning/alerts/{alert_number}/autofix`
- New `/repos/{owner}/{repo}/code-scanning/alerts/{alert_number}/autofix/commits`
- New `/repos/{owner}/{repo}/code-security-configuration`
- Add discriminators for various properties
- New `/repos/{owner}/{repo}/issues/{issue_number}/sub_issues`
- New `/repos/{owner}/{repo}/issues/{issue_number}/sub_issues/priority`
- New `/repos/{owner}/{repo}/secret-scanning/push-protection-bypasses`
- New `/repos/{owner}/{repo}/secret-scanning/scan-history`