Add definitions for helper view schema attributes

[fedorov]

Those were added in ImagingDataCommons/ETL#15, but do not appear in the Google PDP views.

[fedorov]

Clear cache and hard reload did not fix this.

This is the location to try to reduce any confusion: https://console.cloud.google.com/bigquery?p=bigquery-public-data&d=idc_v7&t=quantitative_measurements&page=table

[bcli4d]

The descriptions are in schemas of tables in idc-pdp-staging since v6. It appears that they are lost when Google copies the views from idc-pdp-staging to bigquery-public-data.
I will ask Adler/Nicholas to fix that process.

[bcli4d]

Adler replied:
Hi Bill,

Thanks for bringing this up. We are aware of this issue and it's a shortcoming of the current library we're using to generate the BQ views (a workaround because the BigQuery Data Transfer Service doesn't have built-in support for copying BQ views, only datasets and tables).

We're working on an improved version of the "copy BQ views" step in our pipeline that also solves this issue, but it might take awhile (late Q1 / early Q2) due to other items in our backlog. Please bear with us as we implement a more stable and sustainable fix.

Best,
Adler

[bcli4d]

@fedorov We don't have descriptions for mearsurements_group or segmentations. I think we discussed this once but I can't recall what you said.