Add additional settings fields to org API

[danimeyer]

This PR adds a number of new fields to the Organization struct that are available when getting an org via the REST API. They can be seen in the sample response in the GitHub documentation.

  "default_repository_branch": "main",

  "members_can_delete_repositories": true,
  "members_can_change_repo_visibility": true,
  "members_can_invite_outside_collaborators": true,
  "members_can_delete_issues": false,
  "display_commenter_full_name_setting_enabled": false,
  "readers_can_create_discussions": true,
  "members_can_create_teams": true,
  "members_can_view_dependency_insights": true,

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[codecov]

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[gmlewis]

Thank you, @danimeyer!
LGTM.
Merging.