Query: ColumnMappings to use for TVF/FromSql #21511
Description
SelectExpression has a ctor (also associated public method in SqlExpressionFactory) which takes the TableExpressionBase which acts as the source of the data. This is used for scenarios like TVF/FromSql (which currently works with TPH or non-hierarchy only).
We need to determine which column mappings to use when generating columns from database, since this code path is encountered while not using any particular entity type mapping from model.