Use ⌘/Ctrl+K shortcut to trigger search bar of official site

[yuanlihan]

Feature discussion: https://apachedruidworkspace.slack.com/archives/C030K0Z7S1Z/p1704425833732369

Description

This PR adds shortcut, ⌘+K or Ctrl+K, to trigger the search bar of official site, see below demo

Screen.Recording.2024-01-05.at.11.31.09.mov

This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[asdf2014]

LGTM 👍

[317brian]

The prod site is built by https://github.com/apache/druid-website-src, so this change also needs to be added to that repo for it to be used on the prod site. We'll make a PR for it over there and get it merged. Thanks for doing the hard part @yuanlihan!

[yuanlihan]

@317brian Thank you so much!