fix(admin): build pipeline & deps

[joshuaellis]

What does it do?

• adds esbuild as a dep to the admin package
• sets peerDeps to match the design-system which is lower than what we were targeting incl. on templates so all packages are aligned
• re-exports admin from the strapi package and no longer tries to include the core plugins on a user app level

Why is it needed?

• upgrading projects couldn't resolve esbuild
• peer dep issues in npm projects
• it's NPM specific but the admin package is not at the same level in the node_modules so you can't import it. Because a user has @strapi/strapi declared, we might as well use that and re-export it. We can also import the core plugins there meaning we're another step closer to PNPM working.

How to test it?

• install a project at 4.15.0
• upgrade to experimental manually
• experimental build –> 0.0.0-experimental.1cec6226fe6c8ca4b8404f1ebac8076d5ee5b336
• should build sucessfully

Related issue(s)/PR(s)

• resolves v4.15.1 upgrade: Cannot find module esbuild after installing new deps #18656
• resolves create-strapi-app --quickstart fails with unable to resolve dependency tree  #18652

[github-actions]

Size Change: -7 B (0%)

Total Size: 630 kB

Filename	Size	Change
examples/getstarted/build/runtime~main.********.js	4.28 kB	-11 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
examples/getstarted/build/bb4d0d527bdfb161bc5a.svg	2.33 kB	0 B
examples/getstarted/build/index.html	609 B	0 B
examples/getstarted/build/main.********.js	623 kB	+4 B (0%)

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[joshuaellis]

I actually think this fixes #15992