chore(atomic)!: externalize dependencies

[fpbrault]

This PR removes Headless from the Atomic/Atomic-react bundles.

It does that by replacing the imports with the URL to the correct version of headless in the CDN. This is done with a custom rollup plugin that finds all the imports with AST and replaces them with the corresponding string.

This only happens when building with the DEPLOYMENT_ENVIRONMENT env variable set to "CDN".

https://coveord.atlassian.net/browse/KIT-3181

[github-actions]

Pull Request Report

PR Title

✅ Title follows the conventional commit spec.

Live demo links

• Storybook

• Playwright report

Bundle Size

File	Old (kb)	New (kb)	Change (%)
case-assist	239.2	239.2	0
commerce	337.8	337.8	0
search	407.2	407.2	0
insight	392.1	392.1	0
recommendation	250	250	0
ssr	401.3	401.3	0
ssr-commerce	350	350	0

SSR Progress

Use case	SSR (#)	CSR (#)	Progress (%)
search	39	44	89
recommendation	0	4	0
case-assist	0	6	0
insight	0	27	0
commerce	0	15	0

Detailed logs

search : buildInteractiveResult
search : buildInteractiveInstantResult
search : buildInteractiveRecentResult
search : buildInteractiveCitation
search : buildGeneratedAnswer
recommendation : missing SSR support
case-assist : missing SSR support
insight : missing SSR support
commerce : missing SSR support

[louis-bompart]

good first draft.
Ideally let's use something that leverage an AST to ensure we replacement actual imports.
Moreover, let's add coveo.analytics in the external as well