[ISSUE 390] Production Image Caching

[daphnegold]

Summary

Fixes #390

Time to review: 10 mins

Changes proposed

This PR fixes 2 issues:

• Installs Sharp package (and sub-dependencies) to remove error about image optimization in production using the Image component in next.js
• Images are cached, but we have a read only root directory for Fargate tasks that prevents next.js from writing to its desired directory. Fix that by creating it then adding the nodejs user as owner of that particular directory

Context for reviewers

This one is going to be tough to test individually, but I don't see any more errors in our AWS logs. The cache issue only happens in production.

Additional information

Broken

Fixed

Note: appears the health check endpoint is failing now and causing the task to restart repeatedly, but that's a separate issue.

[SammySteiner]

This one was confusing. Great job!