Fix the build. Split dev from prod. In dev, convert import.meta.env.DEV to DEBUG from @glimmer/env

[NullVoxPopuli]

previously, were kind of compiling away our helpful-information-to-dev-mode users.
but we can't give them import.meta.env either, as our consumers don't have that available.
But they do have DEBUG from @glimmer/env via babel-plugin-debug-macros, so we'll use that.

I also added conditional exports, because:

• in prod mode (aka, someone using from CDN, or other NODE_ENV=production), we want all debug flags removed for performance
• in dev mode, we want to swap our import.meta.env for DEBUG from @glimmer/env so that our current main consumer (ember.js) can still to build-time swapping of values for their dev vs prod environment.

After this PR, I'll do a patch release, and test setting up @glimmer/vm (and friends) in a jsbin, which should hopefully verify that all the prod stuff is configured correctly (this may also be an opportunity to update the js-framework-benchmark to see if anything's different over there

Other changes of note:

• we no longer ship a cjs build, ESM only is what is published
• if consumers need to bundle ESM to something, their existing bundlers can configure that.

[NullVoxPopuli]

lint now depends on publint, which also depends on build.
in another PR, I'll be adding an in-CI turbo server to help with build times

[NullVoxPopuli]

[NullVoxPopuli]

It works! https://jsbin.com/yuwofur/edit?html,output