Missing event toggle fields in SetGroupSlackOptions

Description

The current implementation of the SetGroupSlackOptions struct is missing several boolean fields required to fully configure Slack notifications at the group level.

While the struct currently contains channel override strings (e.g., PushChannel), it lacks the primary event toggles (e.g., PushEvents, IssuesEvents) that determine whether a notification is sent at all.

Requirements

Update the SetGroupSlackOptions struct to include:

Event Toggles: push_events, issues_events, confidential_issues_events, merge_requests_events, tag_push_events, note_events, confidential_note_events, pipeline_events, wiki_page_events, deployment_events, incidents_events, alert_events, commit_events, and job_events.

Pipeline Logic: notify_only_when_pipeline_status_changes.

Settings: use_inherited_settings.

Documentation Reference GitLab Group Integrations API - Set up Slack