Publish sales val flags to open data

[jeancochrane]

We need to put the sales val flags on open data. There is some subtlety to this publishing process, since we need to be able to preserve the state of flags at the time that each yearly ratio study is published so that the ratio study is reproducible. We can probably make this happen by using something like dbt snapshots to produce snapshotted versions of the flags at the time of each ratio study and then publishing those to one or more dedicated open data tables, but this needs some clarification before we move ahead with it.