right panel title

[will-moore]

This allows the right panel of webclient to be customised adding content at the top.

Used by ome/omero-mapr#79

[will-moore]

Failing with

.tox/py310/lib/python3.10/site-packages/django/forms/widgets.py:391: in __init__
    raise ValueError(
E   ValueError: ClearableFileInput doesn't support uploading multiple files.
!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
=============================== 1 error in 1.[98](https://github.com/ome/omero-web/actions/runs/4873403481/jobs/8692946376?pr=463#step:6:99)s ===============================
py310: exit 2 (2.47 seconds) /home/runner/work/omero-web/omero-web> pytest -rf pid=2064
.pkg: _exit> python /opt/hostedtoolcache/Python/3.10.11/x64/lib/python3.10/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  py310: FAIL code 2 (53.36=setup[26.54]+cmd[21.68,0.16,2.50,2.47] seconds)
  evaluation failed :( (53.91 seconds)

See #465