vtkXMLDataParser: track `AppendedData` state explicitly

Bug-Debian: https://bugs.debian.org/1064762
Origin: upstream,https://gitlab.kitware.com/vtk/vtk/-/commit/3efa07ad277efe5c1d11a2ef2b907c095f68bbef
Forwarded: not-needed

Newer `libexpat` doesn't like being given the appended data after the
artificially ended document anymore. Avoid pushing it through to its
parser.

Gbp-Pq: Name 09_newer_expat.patch

vtk9 (9.3.0+dfsg1-1+rpi2) trixie-staging; urgency=medium

  * Change build-depends to libhdf5-mpi-dev
  * Add build-depends on libopenmpi-dev, I'm not sure why this is still
    trying to link against openmpi libs but I need it built.

[dgit import unpatched vtk9 9.3.0+dfsg1-1+rpi2]

Import vtk9_9.3.0+dfsg1-1+rpi2.debian.tar.xz

[dgit import tarball vtk9 9.3.0+dfsg1-1+rpi2 vtk9_9.3.0+dfsg1-1+rpi2.debian.tar.xz]

Import vtk9_9.3.0+dfsg1.orig.tar.xz

[dgit import orig vtk9_9.3.0+dfsg1.orig.tar.xz]