Sort question list by pattern then difficulty

[seanprashad]

#9 made me realize that the question list only looks 'sorted' since the source file, https://github.com/SeanPrashad/leetcode-patterns/blob/master/src/data/index.js, has the question list conveniently sorted already.

However, this will become a problem when we begin adding new questions that add to existing categories, essentially showing the questions out of place.

Let's look into using react-table's UseSortBy method to implement custom sorting by pattern, then difficulty, then question name.

[seanprashad]

Solved via d45088f