Add basepath support to eCR Viewer

[angelathe]

PULL REQUEST

Summary

Add basepath support to the eCR Viewer.

• Add env var NEXT_PUBLIC_BASEPATH="/ecr-viewer"
• Fix basepath references for orchestration integration tests, lighthouse tests, and Cypress e2e tests

Related Issue

Fixes #2536
Also related to #2397

Acceptance Criteria

• Basepath support added to the application
• New release cut (Can only be done after this PR and Fix S3 writes for running instances #2537 are merged to main)
• AWS/Azure are running new code and working as intended (the Viewer can load)

Additional Information

Context:
Without basepath support, the eCR Viewer runs into gateway errors for our CSS/JS files when deployed to a cloud environment.

Testing

• Try running the ecr-viewer in both production and dev modes
  • Production: npm run build then npm run start --> Visit http://localhost:3000/ecr-viewer
  • Dev: npm run local-dev --> Visit http://localhost:3000/

[emmastephenson]

LGTM, but would also love a review from @nickbristow (or anyone with more FE expertise) as it's been a while since I was this in the weeds 😅

[nickbristow]

LGTM, but would also love a review from @nickbristow (or anyone with more FE expertise) as it's been a while since I was this in the weeds 😅

yeah, we paired on this to get it working! LGTM