Potentially convert R plotting for heatmaps to callable functions

[jenna-tomkinson]

Do we expect to include this heart/well-wise feature plotting as routine for future EDAs? If so, it seemed like you've already made the script pretty parametrized so maybe this plotting workflow could be promoted as a function or script in future PRs (or in this PR if you are up for the extra work)?

Originally posted by @wli51 in #7 (comment)