Resolves #831: Reduces calls to Open Processing API to prevent hitting rate limit errors

[clairep94]

Original Issue:

#831

Changes:

• Memoizes getCuratedSketches
• Refactors getSketch(id) to first check in the memoized getCuratedSketches results for an item with matching visualID first, then only calls OpenProcessing API for the individual sketch Id if no memoized item is found
• Destructures properties from getSketch on the SketchLayout -- I thought this increased legibility, but happy to take this out

Notes:

I took a look at removing the call to /api/code which is in getSketchSize

• It seems like /code is used just to get the width and height properties of a sketch
• If it is possible to add width and height to the data for both getCuratedSketches and getSketch(id), I'll make a followup PR to refactor and eliminate the extra API call to /api/code as well!