Shows size of items array in the Settings > Storage tab

[aanand3]

Added functionality to show the size of the current entries list in the Settings modal. Addresses #19.

Notes

• I deliberately left the styling pretty simple, I think by keeping the styling the same as the <Title /> on the left side, it showed that the value had equal importance as the label. It naturally meshed with the other Settings tabs too. Happy to iterate on any feedback.
• The size will currently show as n bytes and then go to n.nn for KB and above.
• The empty array is 2 bytes on it's own... so I subtracted 2 from the calculated value.

Let me know your thoughts!

[aanand3]

@ayoung19 pushed a refac which stores the size in an atom - thanks for the review 🙂