Re #28236

Re #28236

This commit adds a reason for the context menu being disabled in this release.

re: #28104

This commit add a record of the context menu being disabled in the indirect data analysis gui.

re: #28104

The help pages in MantidPlot and MantidWorkbench were not using the custom Mantid
style sheet. This could be seen by the fact the hyperlinks were blue for example
instead of green.
These changes force the Qthelp pages to use the bootstrap theme by setting the
options qthelp_theme and qthelp_theme_options which seem be be new in recent
Sphinx versions. Previously Qthelp just shared the html_theme\html_theme_options
settings with the Html help.

Remove spurious FileFinder call

In workbench warnings shown as errors mean't that any deprecation
warnings would show as errors when in fact a script should still complete
successfully. This captures them at the correct level.