Write tests related to the `adopted` column

[Condensed from https://github.com/SIMPLE-AstroDB/SIMPLE-db/issues/84]

Tests should fail if there are multiple measurements set as 'adopted'. That is, if set to false/null they would not trigger a failure, just when you have 2 or more entries set to true.

[On hold until a table with an adopted column is added to the template database: https://github.com/astrodbtoolkit/astrodb-template-db/issues/37)

Start by reviewing the existing test suite and how tables with an `adopted` column are represented. The issue is on hold until astrodb-template-db issue 37 adds a suitable table; once available, add coverage showing that two or more `true` measurements fail while zero or one `true` measurement passes.

Written by the indexing model from the issue text.