Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38795
## Context
RFC: Decoupling Flipper from React Native core: https://github.com/react-native-community/discussions-and-proposals/pull/641
## Changes
Inits new package `react-native/community-cli-plugin`. This migrates [`react-native-community/cli-plugin-metro`](https://github.com/react-native-community/cli/tree/main/packages/cli-plugin-metro) into the React Native repo, to enable faster iteration by the React Native core team. Specifically:
- This package contains several `metro` dependencies, which when removed from CLI will no longer require us to ship new CLI releases to get Metro patches and features to users.
- This package contains the `start`, `bundle`, and `ram-bundle` commands (central to the React Native development experience), for which we have incoming debugging-related changes.
- This package now **only** exports commands to be attached via a RN CLI plugin. With this move, we're aiming to **internalise** the default implementations of these dev commands within React Native — other RN CLI plugins can continue to override these, but must do so wholesale. (See also the recent fix for this: https://github.com/react-native-community/cli/pull/1999.)
In V15:
- (Microsoft feedback) Re-export `unstable_buildBundleWithConfig`, marking as unstable. This gives us a time buffer to consider how we repackage this functionality in future.
The package source has been converted from TypeScript to Flow, with a number of new `flow-typed/` defs added to meet type coverage requirements.
## To dos
- For now, we aren't removing the existing [`react-native-community/cli-plugin-metro`](https://github.com/react-native-community/cli/tree/main/packages/cli-plugin-metro) source — until later PRs consolidate this move by changing dependencies in the `react-native` package.
- **Exported API is reduced!**: I'm working with szymonrybczak to decouple references from RN CLI packages https://github.com/react-native-community/cli/pull/2021.
Changelog: [Internal]
Reviewed By: motiz88
Differential Revision: D46801501
fbshipit-source-id: 7f6b72941a69f487fb437768cdba125a9aa3418d
