RFE: keyboard shortcut to redisplay search results

# Feature request

### Motivation

When the option to "Automatically hide and show the sidebar" is selected, navigating to a search result closes the sidebar. However, sometimes there are multiple search results and the one you pick first turns out to be not what you need, but by then the sidebar is already hidden and you don't see the rest of the search results.

It is possible to redisplay the search results by typing something else or using Alt + ↓ / ↑, but that's unintuitive/inconvenient because it resets search results and/or clobbers the cursor position.

### Summary

This RFE is to add a dedicated keyboard shortcut (for example, Alt + /) to refocus the sidebar and redisplay search results, without changing them in any way.

Sometimes the search results disappear completely (such that the Alt + ↓ / ↑ workaround does not help). This shortcut should be able to refresh the search in this case.

This request is similar to #657, but for a keyboard shortcut rather than mouse gesture.

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There are also apparent inconsistencies in how / is handled (it's not really useful most of the time because in normal usage the search bar does not seem to lose the focus at all, so blindly typing / after navigating to a search result tends to just insert a stray literal `/` into the search box). Perhaps this could be changed and then `/` would serve as the shortcut for this RFE?

### Examples

N/A

The issue names no source file, test, or entry point; start by locating the sidebar, search-results, and keyboard-shortcut handling. The work is done when a dedicated shortcut restores the existing search results without changing them, including when the results have disappeared, and the behavior is covered by verification.

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