Add support for a summary view of org teams.

[david-bain]

Add a flag input to optionally skip returning the repositories and members on calling the github_organization_teams data source. This improves performance of the graphql call when only summary information is needed. Especially important on orgs with large numbers of teams/members.

• Add summary_only optional flag input to skip returning members and repositories
• Add 'results_per_page' optional int to reduce the results per page returned.
• Update docs to reflect change