Add Support for tabular data entry in Bulk Search

[benbdeitch]

Closes #9699

This PR adds another new child of the AbstractExtractor class. The TableExtractor allows for data to be copy-pasted from Google Sheets or other spreadsheet services, and extracts the contents of the 'title' column and the 'author' column, if they exist.

Technical

Currently, the implementation allows for titles to be searched if the author column is empty. This has led to an odd interaction, where searching for 'Mark Twain' in the title ends up incorrectly pulling other books that he wrote. I'll be debugging that over the next day or so, but I figured I might as well put it up for review.

Testing

Create a table in Google Spreadsheets, then copy it into the input area of the /search/bulk page. Select the bottom extraction option, and click 'extract books'. Please ensure that you have titled your columns appropriately.

Screenshot

Stakeholders

@cdrini