Compile Figure 3

[allyhawkins]

Closes #44 Stacked on #58

This PR adds in a compiled version of Figure 3. Originally, we had talked about showing the individual SCE object download structure, then the merged workflow, and then the merged download illustration, but that doesn't look the best on the page. I chose to show both download structures as A and B and then the merged workflow as C.

• Since we do want to show the download illustrations here for both individual SCEs and merged SCEs, I added those pngs to the repo here.
• For the merged workflow, I changed all the icon labels to Arial size 8.
• For the UMAPs, I chose to use the png and then re-do each of the labels. The pdf was very large since it's 4 UMAPs that each have a merged object, so lots of little points. Here all the text is Arial size 8.

[allyhawkins]

@jaclyn-taroni I made panels A, B, and C bigger so the font sizes should be bigger. I also readjusted the alignment for the output data labels in panel C and then increased the font size for panel D.

The last thing I did was update the organization to follow https://github.com/AlexsLemonade/scpca-paper-figures/pull/49#issuecomment-1938884084.