[feat]: add custom-elements-manifest analyzer

[bennypowers]

Steps:

1. add @custom-elements-manifest/analyzer as devdep to all templates
2. add analyze script to all templates
3. profit

cc @thepassle

[thepassle]

Some things to think about are:

• Do we want to add the CEM to the users .gitignore, and then make sure the analyzer runs on prepublish?

I know some people have strong opinions on code reviews/making sure that the CEM has updated correctly, I also know people wont like seeing CEM changes in their PRs necessarily, so we'd have to make some kind of decision there.

• When do we run CEM?

Clever cloud starts the analyzer in watch mode kind of as a side effect of the web dev server config, so the analyzer will always run when the server runs. We could also consider creating a separate dev-server plugin to run the analyzer, maybe thats a bit 'cleaner'.

It would be nice to have the analyzer run in watch mode especially when the new version of storybook releases and makes its way into storybook-prebuilt, because then users will have up-to-date knobs/controls as they write code.

[bennypowers]

i think we shouldn't check the manifest in. imo it's a build artifact
for the dev server plugin, I think we should develop that separately, then add it here as a feat.

should that plugin live in cem repo or dev server repo cc @LarsDenBakker
we have infra to add a plugin to cem repo, seems natural to me to put it there

[thepassle]

i think we shouldn't check the manifest in. imo it's a build artifact

I agree. Maybe we go with that for now, we can always change it

should that plugin live in cem repo or dev server repo cc @LarsDenBakker

I think its fine to add it to the cem repo

[bennypowers]

ok i'll start here then swing back to the build plugin if i have time