support fetching user insights reports

[mrmauer]

Tests

TKTK

After PR

now you can...

let top_inviters_page = auth.reports().fetch_user_top_inviter_report(
    TopInviterReportInterval::ThirtyDays,
    ReportPagination {
        page_size: Some(10), // default 10 for all report fetches
        page_number: Some(0), // defaults 0 for all report fetches
    }
).await?;

let champions_page = auth.reports().fetch_user_champion_report(
    ChampionReportInterval::ThirtyDays,
    ReportPagination::default(),
).await?;

let user_churn_page = auth.reports().fetch_user_churn_report(
    ChurnReportInterval::SevenDays,
    ReportPagination::default(),
).await?;

let user_reengagement_page = auth.reports().fetch_user_reengagement_report(
    ReengagementReportInterval::Weekly,
    ReportPagination::default(),
).await?;

let org_churn_page = auth.reports().fetch_org_churn_report(
    ChurnReportInterval::ThirtyDays,
    ReportPagination::default(),
).await?;

let org_reengagement_page = auth.reports().fetch_org_reengagement_report(
    ReengagementReportInterval::Weekly,
    ReportPagination::default(),
).await?;

let org_growth_page = auth.reports().fetch_org_growth_report(
    GrowthReportInterval::ThirtyDays,
    ReportPagination::default(),
).await?;

let org_attrition_page = auth.reports().fetch_org_attrition_report(
    AttritionReportInterval::ThirtyDays,
    ReportPagination::default(),
).await?;