Changes to Self-service usage, budget, and rate limit status

added the optional property budgets/items/enforced_cost_basis to the response with the 200 status

added the optional property budgets/items/cost_basis to the response with the 200 status

added the optional property usage/total_billed_cost to the response with the 200 status

added the new optional query request parameter cache_mode

added the new internal_error enum value to the error/type response property for the response status 400

added the new internal_error enum value to the error/type response property for the response status 401

added the new internal_error enum value to the error/type response property for the response status 503

added the new permission_error enum value to the error/type response property for the response status 400

added the new permission_error enum value to the error/type response property for the response status 401

added the new permission_error enum value to the error/type response property for the response status 503

added the optional property error/provider to the response with the 400 status

added the optional property error/provider to the response with the 401 status

added the optional property error/provider to the response with the 503 status

added the optional property budgets/items/per_child to the response with the 200 status

added the optional property rate_limits/items/per_child to the response with the 200 status

added the optional property rate_limits/items/subject to the response with the 200 status

added the optional property budgets/items/scope to the response with the 200 status

added the optional property budgets/items/subject to the response with the 200 status

endpoint added