Add the scan_data() function

[rich-iannone]

Having a function to provide a comprehensive summary of a table would be valuable for understanding a dataset. Having scan_data() could quickly provide the user with:

• an overview of the table (e.g., dimensions, etc.)
• a stats summary for each column
• interactions between variables
• correlations across variables
• a report of missing values in the table
• a preview of the dataset in a small table