Based on review comments, revert the isHistogramData method to its
original form without any parameters to avoid encouraging creation
of matrix workspaces containing histograms with mix of xModes
Create private function instead that allows a specific histogram to
be checked

The unit test suite MonteCarloAbsorptionTest has occasionally been failing
with an access violation on Jenkins. I've been able to track this down to
the test Lambda_StepSize_Two_Linear_Interpolation which was failing

I can reproduce this locally by modifying the test to repeat 1000 times
and it eventually fails. Although the access violation occurs in a couple
of different places:
a) the y() or e() vector in the 0th histogram is sometimes empty once the
MonteCarloAbsorption algorithm completes which causes some of the test asserts
to fall over because they assume y(0).front() or e(0).front
b) sometimes the code in MonteCarloAbsorption itself has an access violation
when yIndexOfX returns an index out of range of the histogram

Both problems happen in the multi-threaded code in MonteCarloAbsorption and
it seems to be the interaction between the call to MatrixWorkspace::yIndexOfX
and the code that updates a histogram with interpolated results via
MatrixWorkspace::setHistogram. Something in these two functions isn't threadsafe
I found that yIndexOfX calls IsHistogramData() which checks the 0th
histogram in the workspcae even if the MonteCarloAbsorption code is
processing the 1st, 2nd etc workspace
I think if the 0th histogram is in the process of being updated by another
thread then yIndexOfX can fail or else the setHistogram call fails.
I have done two changes:
- only call yIndexOfX once (there was a redundant 2nd call)
- I have modified yIndexOfX so it takes an additional histogram index parameter.
This allows me to keep each MonteCarloAbsorption thread interacting with a
single histogram only. I have defaulted the new parameter to zero so other
code behaves as before

Adding sphere integration tests

Fix key/completer handling in AddFunctionDialog

Fix Muon Analysis fit browser crash

Fix Windows package OpenGL issue over remote connection

Merge pull request #29628 from mantidproject/0_FixAnIssueWithRecentlyClosedScriptsThrowingErrorsWithGarbageData

Recently Closed Scripts: TypeError handling where garbage data is gound

Also in this commit plot guess is turned off by default when loading new data.

Added a view test to catch this behaviour
Refs #29620

Adds a test of the view using the QtTest framework
Refs #29620

Unsupported instruments in DrILL

Adds a check on the selected algorithm when opening the settings dialog.
This avoids a crash if an unsupported instruments has been selected.

Log an error if the user changes the facilty and DrILL is shown.

The connection to the instrument selector widget is removed when the
DrILL interface is closed. That avoids error messages coming from the
interface when it is not

Removes the filering of instruments in the instrument selector widget of
DrILL. This avoids a wrong instrument selection in DrILL if the user
selected an unsupported instrument in workbench global settings.

Geometry code cleanup

Add separate page for Sliceviewer release notes

Format release notes for 5.1.0 Diffraction, Muons, LSS and Spec

Co-authored-by: DanielMurphy22 <daniel.murphy@stfc.ac.uk>

Refs #29325. Enable workbench to have plot menu for MDHistoWorkspace.

Co-authored-by: DanielMurphy22 <daniel.murphy@stfc.ac.uk>

Merge branch '29325_workbench_plot_md' of github.com:mantidproject/mantid into 29325_workbench_plot_md