[Bug]: Avoid flash-of-missing-image when creating new workflow

[ikreymer]

Browsertrix Cloud Version

v1.8.0

What did you expect to happen? What happened instead?

When creating a new workflow, occasionally can see the dialog without images while images load (usually first time / if cache expired).

Perhaps this can be fixed with a skeleton, or other ways of fixing the layout while images load?

Step-by-step reproduction instructions

1. Open devtools, disable cache
2. Click create new workflow page, try a few times if needed
3. Will likely see result in screenshot.

Additional details

No response