Warn users before executing an automatic change of context

[hostle83]

Describe the bug
According to WCAG 2 Success Criterion: 3.2.2 On Input (A), users should be warned before a change of context occurs on a site. As an example, when searching (https://sandbox.dspace.org/search?query=), use of the slider functionality in the Date filter reloads the page without giving the user a warning of that change or giving them the option to activate the reload themselves. See https://www.w3.org/WAI/WCAG21/Understanding/on-input.html for reference.

This behavior is consistent across all search filters.

To Reproduce
Steps to reproduce the behavior:

1. Visit the search page on the sandbox, demo, or localhost (.../search?query=)
2. Expand any search filter
3. Adjust the search by using any filter, such as using the date slider to filter search results --> page reloads each time slider is used; the same holds true for all other search filters

Expected behavior
Either warn the user of the change of context (reload) beforehand, or give the user to activate the change themselves by providing a button or similar functionality

[atarix83]

@tdonohue @hostle83

4science is interested in working on this task.
In order to fix the problem we'd add an additional button to apply the date range filter. Estimation is about 6h

[tdonohue]

Closing as fixed by #3236. Ported to 8.x and 7.6.x.