Search menu keyboard control

[AzulRadio]

New feature

Summary

Now we can navigate the search menu with ↑ ↓ arrow keys and use Enter to select.

Test it

Try it!

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #403 (8cc78c8) into ign-gui6 (5c09688) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           ign-gui6     #403   +/-   ##
=========================================
  Coverage     30.54%   30.54%           
=========================================
  Files            41       41           
  Lines          1748     1748           
=========================================
  Hits            534      534           
  Misses         1214     1214           

Impacted Files	Coverage Δ
include/ignition/gui/qrc_resources.cpp	100.00% <0.00%> (ø)

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[jennuine]

Requesting minor change but otherwise works great!