A struct representing a pivot report response

Has the following keys:

• dimensions: a list of the dimension in the report
• metrics: a list of the metric names in the report as well as their type, in tuple format e.g. {"activeUsers", "TYPE_INTEGER"}
• pivot_headers: the names for each 'column'
• rows: a list containing the row's data
• totals: used for reports with total
• count: the number of rows
• aggregates: aggregate data (if returned)
• property_quota: property quota data (if returned)
• metadata: associated with the report and property, such as currency code, time zone information and if the data is subject to thresholding.

Implements the Table.Reader reader protocol.