Update links and misc. cleanups to account for `docs.vtk.org` and `book.vtk.org`

This merge request implements the following changes:

book

• Simplify VTKBook.md and reference https://book.vtk.org

• Remove obsolete VTKBook files and update ScrapeRepo.py

  • Development of the markdown book moved into its own repository at https://github.com/Kitware/vtk-book and is published at https://book.vtk.org

examples

• Update book chapter links. For example:

  (../../..//VTKBook/05Chapter5) -> (https://book.vtk.org/en/latest/VTKBook/05Chapter5.html)
  (../../../VTKBook/06Chapter6) -> (https://book.vtk.org/en/latest/VTKBook/06Chapter6.html)
  (../../../VTKBook/01Chapter1/) -> (https://book.vtk.org/en/latest/VTKBook/01Chapter1.html)

• Update book figure links. For example:

  (../../../VTKBook/06Chapter6/#Figure%206-44) -> (https://book.vtk.org/en/latest/VTKBook/06Chapter6.html#figure-6-44)

• Update VTKFileFormats links. For example:

  (../../../VTKFileFormats -> (https://docs.vtk.org/en/latest/design_documents/VTKFileFormats.html

docs

• Remove obsolete VTKFileFormats.md file and update ScrapeRepo.py
  • The file was moved into the VTK repository.