Search result tweaks for autocomplete

[joelit]

Link to relevant issue(s), if any

• Vocab search field in header bar #1514

Description of the changes in this PR

• Filtered duplicate results with unique=true parameter. This changes the amount of search results recieved
• Alternate labels are displayed in italics
• Notation codes are shown if showNotation configuration parameter is set for the vocabulary
• Notation code results are returned and bolded if they match the search term

Known problems or uncertainties in this PR

The language for the search is not set yet. That fuctionality should come in the follow-up pull request.

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[UnniKohonen]

Everything seems to work as intended. Added a very minor suggestion to code but this can be merged IMO.

[sonarcloud]

Quality Gate failed

Failed conditions
37.8% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud