[#105] Add Classification page

This MR implements the Text Classification page.

• The input autosizes to support multiple lines of text
• The edit modal can be used to edit in a larger text area
• Text can be extracted from a document and appended to the input value
• Closing the modal while extracting text cancels the request
• The list of results can be filtered by score range
• The abstract returned by the API can be toggled on/off and is displayed in a scrollable area