Refactor Intl polyfills and remove from ES5 entrypoints

[steverep]

Proposed change

This change drastically reduces the entrypoint sizes for the ES5 build by removing the FormatJS Intl polyfills and loading them with the same timing logic as the latest build. It also greatly simplifies use of Intl where desired by only requiring a single import. Steps are roughly:

1. Split the dynamic import and top level await version for the latest build into its own module. Also split out the locale data polyfill function so there's no circular dependency.
2. Move the TLA to the new intl-polyfill module, and just write code to import it before using Intl.
3. Split the static import version for the ES5 build as well. Code is written for latest build, but Webpack makes the swap for the ES5 build.

And here's the result on the ES5 build:

ES5 Entrypoint	Old	New
app	582K	596K
core	2.1M	345K
custom-panel	2.0M	317K
authorize	2.5M	859K
onboarding	2.7M	1.1M
Total Bundle	36M	32M

And as a happy accident, the latest build entries go down a little too. This is because the connection mixin is no longer importing the localize module early:

Latest Entrypoint	Old	New
app	315K	293K
core	19K	19K
custom-panel	35K	35K
authorize	388K	367K
onboarding	417K	395K
Total Bundle	26M	26M

I mean... I knew that was going to happen. 🦊

This may actually fix the Webpack upgrade issue as well because that's reportedly related to conditional TLAs, which are eliminated here. I'll have to check that out.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[steverep]

I'm adding 2 corrections here:

1. Dynamic imports should use the polyfill-force options so as not to repeat the shouldPolyfill checks.
2. English locale data must be imported after the corresponding polyfill.

There are other corrections/improvements that I noticed could be made, but I'll save those for a follow up and list in an issue before I forget.

Also, these polyfills are still plaguing the supervisor entrypoints (see #15956). Some extra savvy is needed to fix that.

[steverep]

Did you want to wait on 2023.6 for this one?

[bramkragten]

Did you want to wait on 2023.6 for this one?

yeah, I'll merge it on thursday if that doesn't stop your from continuing something else? Otherwise we can also merge now, then I'll just cherry pick

[steverep]

There's more that requires this, but also plenty to do that doesn't. No big deal to wait or just work with a stash. 👍🏻

[steverep]

FYI, this does indeed fix the ability to upgrade Webpack (ref: webpack/webpack#16097).