The function checkBookAvailability accepts an array of book
objects, referred to as inventory, and a specified book title,
denoted as requestedTitle. Each book object contains properties
title and copiesAvailable.
The function checks whether the requested book is present
and available in the inventory.
For example, if the book The Namesake is available in the
inventory, the function should return,
"The book 'The Namesake' is available in stock."
If the book is not available in the inventory or the number
of available copies is 0, it returns a message indicating
that the book is currently out of stock.
For example, if the book The White Tiger is not in stock,
the function should return
"Sorry, the book 'The White Tiger' is currently out of stock."