build: ui copying to be part of browser's vite build

[AriPerkkio]

When using browser feature in local development with pnpm dev, the browser package's pnpm copy is not run at all. UI in browser is a blank white page as packages/ui has not been copied there.

This PR adds ui copying to be part of pnpm dev workflow. It also makes sure monorepo's pnpm build command runs packages/browser as last step to make sure packages/ui has been completely built before copying it.

Tested manually using locally linked package + test/browser.

[sheremet-va]

While we are here, I noticed some dependencies in the browser should be moved to "dev". From @vitest/runner we only need types, so it can be moved. rollup-plugin-node-polyfills, local-pkg, and mlly are not used at all. Can we remove them in this PR, or should we split it?

[AriPerkkio]

Let's include it in this PR. I'll go through browser package's dependencies and check how they are used.

[userquin]

@sheremet-va if browser package runs before ui package the browser dist/client/__vitest__ folder will be empty (I can test this PR on my Windows laptop, current version always build browser before ui package on my local builds).

[sheremet-va]

@sheremet-va if browser package runs before ui package the browser dist/client/__vitest__ folder will be empty (I can test this PR on my Windows laptop, current version always build browser before ui package on my local builds).

Please, read the previous conversation: #3137 (comment)

browser is always built after the ui.

[AriPerkkio]

runs before ui package the browser dist/client/__vitest__ folder will be empty

There is also a check for this in browser package's build. This will trigger if packages/browser is somehow built before packages/ui, or that in local environment the developer tries to manually build only the packages/browser.

vitest/packages/browser/src/client/vite.config.ts

Lines 23 to 28 in b9d6b7e

	const ui = resolve(root, 'ui/dist/client')
	const browser = resolve(root, 'browser/dist/client/__vitest__/')
	const timeout = setTimeout(() => console.log('[copy-ui-plugin] Waiting for UI to be built...'), 1000)
	await waitFor(() => fs.existsSync(ui))
	clearTimeout(timeout)