Live preview e2e tests had no CSS when tested against prod.
For all our other tests, we have a separate test/app directory that
imports CSS. Otherwise, the root-level /app directory is used.
For live-preview, we currently always run against test/live-preview/app,
that has no CSS import.
This PR adds a new test/live-preview/prod/app directory that imports CSS
and is used when we run tests against prod.
In order for this to work, I had to make import map generation smarter
This noticeably improves performance in the admin panel, for example
when there are multiple richtext editors on one page (& likely
performance in other areas too, though I mainly tested rich text).
The babel plugin currently only optimizes files with a 'use client'
directive at the top - thus we have to make sure to add use client
wherever possible, even if it's imported by a parent client component.
There's one single component that broke when it was compiled using the
React compiler (it stopped being reactive and failed one of our admin
e2e tests):
150808f608
opting out of it completely fixed that issue
Fixes https://github.com/payloadcms/payload/issues/7366
