silx view: Added --slices option

[t20100]

This PR adds the option to pass multiple integers for displaying slices with silx view through a --slice option.

To do so, it adds a DatasetSlice class to expose the opened slice as a dataset and makes the necessary changes to make it work.

The content of this PR is adapted from PR #3677 (which was hard to rebase).
It is a simpler version of PR #3677 since it only provides --slice and not URL #fragment support which could be added later if needed.

[t20100]

I'm not a fan of having specific code for DatasetSlice here, but I couldn't find a better way, except maybe adding this in the silx.io.commonh5 API...

[t20100]

Same, it'd be best to avoid specific code here.
I wanted to rework the way to check equality, but that's complex changes

[t20100]

CI fails a lot on Windows with python3.7 and pyside6, with exceptions like:

    def tearDown(self):
        self.qapp.processEvents()
    
        if len(self.__class__._exceptions) > 0:
            messages = "\n".join(self.__class__._exceptions)
>           raise AssertionError("Exception occured in Qt thread:\n" + messages)
E           AssertionError: Exception occured in Qt thread:
E           Traceback (most recent call last):
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViewer.py", line 290, in __setDataInView
E               if (self.__previousSelection.slice != self.__displayedSelection.slice or
E           AttributeError: 'NoneType' object has no attribute 'slice'
E           Traceback (most recent call last):
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViewer.py", line 290, in __setDataInView
E               if (self.__previousSelection.slice != self.__displayedSelection.slice or
E           AttributeError: 'NoneType' object has no attribute 'slice'
E           Traceback (most recent call last):
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViewer.py", line 290, in __setDataInView
E               if (self.__previousSelection.slice != self.__displayedSelection.slice or
E           AttributeError: 'NoneType' object has no attribute 'slice'
venv_test\lib\site-packages\silx\gui\utils\testutils.py:188: AssertionError

    def tearDown(self):
        self.qapp.processEvents()
    
        if len(self.__class__._exceptions) > 0:
            messages = "\n".join(self.__class__._exceptions)
>           raise AssertionError("Exception occured in Qt thread:\n" + messages)
E           AssertionError: Exception occured in Qt thread:
E           Traceback (most recent call last):
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViewer.py", line 287, in __setDataInView
E               self.__currentView.setData(self.__displayedData)
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViews.py", line 657, in setData
E               self.__updateDisplayedView()
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViews.py", line 635, in __updateDisplayedView
E               w = self.__currentView.getWidget()
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViews.py", line 351, in getWidget
E               self.__widget = self.createWidget(self.__parent)
E             File "C:\projects\silx\venv_test\lib\site-packages\silx\gui\data\DataViews.py", line 1347, in createWidget
E               widget = RecordTableView(parent)
E           AttributeError: __init__
venv_test\lib\site-packages\silx\gui\utils\testutils.py:188: AssertionError

[vallsv]

I think it would be better to use a real slice here

--slice 1,2,3

instead of

--slice 1 2 3

As we already have the parser from the DataUrl, it's costless, and it will support stuffs like 1::2,:10,...

[t20100]

--slice 1 2 3 opens not just one slice (data[1,2,3]) as a dataset but 3 slices as 3 different datasets: data[1], data[2], data[3].
Maybe best to call it --slices.

I haven't done it, but we could also support --slice 1::4,:10,...,1 3:5,:,1 if needed.... but the current main need is to open slices in a 3D stack.

[payno]

work smoothly on my datasets

[t20100]

• Fixed CI: Updated python used to test with pyside6 in order not to restrict matplotlib version.
• Changed option from --slice to --slices

Finally ready for review/merge

[payno]

still fine with me.
Maybe we could add an example on how to use it on the PR and on the text documentation (view.rst/ Examples of usage) as well like:

# open specific dataset
silx view 5.06_crayon_W150_60_Al2_W0.25_xc1000_.nx::entry/instrument/detector/data
# open specific set of dataset from name / location
silx view 5.06_crayon_W150_60_Al2_W0.25_xc1000_.nx::entry/*/data
# open specific set of datasets slices (first and last on this example)
silx view 5.06_crayon_W150_60_Al2_W0.25_xc1000_.nx::entry/*/data --slices 0 -1

[t20100]

I added your examples (reworked a bit) to the doc, including

silx view my_hdf5_file.h5::entry/*/data --slices 0 -1

I also fixed an (unrelated) issue with building the doc