#3359118: Allow table cells to have text formats applied

Allows cells in formatted tables to have a text format applied to the contents.

• Adds use_text_format and text_format config to FileTableFormatter
• Passes config through to FileTableFormatterProcessor
• FileTableFormatterProcessor takes format and, if it's set, applies it to the table cell contents
  • Applies to headers too since it uses the same processing
• Add schema file with FileTableFormatter schema definition
• Pass services used in FileTableFormatter via create method
• Bit of PHP type enforcement