Import total lanes from reconciler

[rickhanlonii]

Overview

This PR attempts to re-add the changes from here that were reverted to unblock main.

The test fails because we're importing from the reconciler without mocking/forking the ReactFiberHostConfig.

[sizebot]

Comparing: 2e8bbcb...50813fe

Critical size changes

Includes critical production bundles, as well as any change greater than 2%:

Name	+/-	Base	Current	+/- gzip	Base gzip	Current gzip
oss-stable/react-dom/cjs/react-dom.production.min.js	=	122.55 kB	122.55 kB	=	39.48 kB	39.48 kB
oss-experimental/react-dom/cjs/react-dom.production.min.js	=	129.13 kB	129.13 kB	=	41.53 kB	41.53 kB
facebook-www/ReactDOM-prod.classic.js	=	406.12 kB	406.12 kB	=	75.38 kB	75.38 kB
facebook-www/ReactDOM-prod.modern.js	=	394.47 kB	394.47 kB	=	73.49 kB	73.49 kB
facebook-www/ReactDOMForked-prod.classic.js	=	406.13 kB	406.13 kB	=	75.38 kB	75.38 kB

Significant size changes

Includes any change greater than 0.2%:

(No significant changes)

Generated by 🚫 dangerJS against 50813fe

[acdlite]

Put it in shared? Or hard coding it seems fine, honestly

[bvaughn]

I'm not completely against hard-coding but it makes me uneasy. Maybe if we had some static check that CI ran to ensure they were the same 😅

I'm concerned that dev tools get broken too frequently by changes in packages like reconciler. It's too easy for people to forget or overlook.