Direct connect, delayed query

When working with large datasets via Direct Connect, eg via Azure SQLDB, the default choice when selecting a field in the well is not always appropriate. For example you might want to count a high cardinality text field. In the current preview, as you select the field, it tries to go get all the individual values (potentially millions) to display. The idea is to have a "delayed calculate/query" selection mechanism where you can prepare fields and filters and then hit go.