[FEATURE] Add autocomplete in the Omnibox

[ryankwirth]

Purpose

Autocomplete (or automatic suggestions) improve discoverability of key search terms and help users avoid common misspellings.

💡 Proposed Implementation:

• Create a context for sharing incidents throughout the component tree
• Extract Fuse.js-related code from the Sidebar component into a separate hook
• Create a dropdown list in the Omnibox component
• Populate the dropdown list with results from the search hook when the input changes