feat: allow sorting by Number of Atoms

[bodom0015]

Problem

We would like to display/sort by the number of atoms in each molecule

Fixes #76

Relates to moleculemaker/mmli-backend#30

Approach

• Added new option to sort by "Number of Atoms" - this is now returned from the API as atom_count

How to Test

This is currently deployed on chemscraper-frontend-staging

1. Navigate to https://chemscraper.frontend.staging.mmli1.ncsa.illinois.edu/results/02b0034a-4335-4823-8d5d-915b54173995
2. Click on the Sort options at the top-right of the table (default: "Location in PDF")
   • You should see a new option here for "Number of Atoms"
3. Choose to sort by "Number of Atoms"
   • You should see the table reorder itself to sort by atom_count
4. Click the blue button on the popover to change whether to sort by ascending or descending