[5.2] Allow multiselect for checkboxes

[laoneo]

Summary of Changes

Restores multiselect behavior when SHIFT key is pressed in back end list views.

Testing Instructions

• Create 5 articles in the back end.
• Select the first one in the list
• Hold SHIFT key and select the last one

Actual result BEFORE applying this Pull Request

First and last one is selected and the text in between.

Expected result AFTER applying this Pull Request

All articles are selected and no text.

Link to documentations

Please select:

• [ ] Documentation link for docs.joomla.org:

• [x] No documentation changes for docs.joomla.org needed

• [ ] Pull Request link for manual.joomla.org:

• [x] No documentation changes for manual.joomla.org needed

[fgsw]

I have tested this item :white_check_mark: successfully on e4ff486f540eb11d78d60ad493bc92ca6c73664f

Test by using prebuilt package.

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[LadySolveig]

I have tested this item :white_check_mark: successfully on e4ff486f540eb11d78d60ad493bc92ca6c73664f

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[brianteeman]

I have tested this item :white_check_mark: successfully on c8ee38ca3f358c8d8172c45f82e3459fb2707d32

thank you!!

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[viocassel]

I have tested this item :white_check_mark: successfully on c8ee38ca3f358c8d8172c45f82e3459fb2707d32

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[Quy]

RTC

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