Implement a function to highlight keywords in text.
Function Signature:
function highlight(keyword: string, text: string): string;
Part 1: Basic Implementation Example:
Input: keyword = "fig", text = "figma"
Output: "<b>fig</b>ma"
Part 2: Overlapping Matches Example:
Input: keyword = "ana", text = "banana"
Output: "b<b>anana</b>"
Note: NOT "b<b>ana</b>na" - maximize coverage
Part 3: Multiple Keywords