report: convert to ES modules

[connorjclark]

ref #12689, #12623

• converts report/renderer and report/test/renderer to ES modules
• adds package.json {type: 'module'} to a couple folders, to be removed when root package.json is esm
• report-generator.js now reads standalone.js from disk, which is generated by yarn build-report. This file is not checked into source control, but will be published. moved to misc(build): add build step for report #12707
• separate builds for each report entry
• temporary: copy and convert to commonjs report/renderer/util.js to lighthouse-core/util-commonjs.js. Remove when ☂️ Convert to ES modules #12689 is done
• temporary: add viewer.js report client that simply sets some renderer classes to window. Remove when viewer is converted to ES modules. Same for treemap

CDT CL: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2939422
PSI CL: cl/377963333

[connorjclark]

this file should be temporary... once viewer is es modules this just goes away.

[patrickhulce]

WDYT about breaking this up a smidge further? it seems like the build process pieces could be in place even without the esm conversion and separate quite cleanly without much effort?

I might be misestimating the level of effort required for that, so quick gut check first :)

[connorjclark]

CDT CL is fully passing its tests now. Once this PR merges we can land that and the PSI CL.

The CDT integration test is presently failing with this PR, which is expected. It will be passing again when the CDT CL lands. Then I'll re-enable it as a required check.