Align Flow lib defs for Node.js os with v24 (#55014)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55014

This is an AI-assisted change to align the Flow definitions for the `os` module with the Node.js docs as at v24.

**New APIs:**

1. **`machine()`** - Returns machine type (added in v18.9.0, v16.18.0)
   - Returns hardware name: `'x86_64'`, `'arm64'`, `'aarch64'`, etc.
   - Different from `arch()` which returns the architecture Node.js was compiled for
   - https://nodejs.org/api/os.html#osmachine

2. **`version()`** - Returns kernel version string (added in v13.11.0, v12.17.0)
   - Example: `'Linux 5.15.0-1234-generic'`, `'Darwin Kernel Version 21.6.0'`
   - https://nodejs.org/api/os.html#osversion

3. **`setPriority([pid,] priority)`** / **`getPriority([pid])`** - Process priority management
   - Set/get scheduling priority for processes
   - Priority constants available in `os.constants.priority`
   - https://nodejs.org/api/os.html#ossetprioritypid-priority
   - https://nodejs.org/api/os.html#osgetprioritypid

4. **`devNull` constant** - Path to null device (`'/dev/null'` on POSIX, `'\\\\.\\nul'` on Windows)
   - https://nodejs.org/api/os.html#osdevnull

5. **`constants` object** - OS constants (signals, errno, priority, dlopen)
   - `constants.signals` - Process signal constants
   - `constants.errno` - Error number constants
   - `constants.priority` - Process priority constants (PRIORITY_LOW, PRIORITY_HIGH, etc.) - Readonly
   - `constants.dlopen` - Dynamic library loading constants
   - https://nodejs.org/api/os.html#os-constants

**Type Safety Improvements:**

6. **`arch()` return type** - Now includes all 10 supported architectures:
   - Added: `'loong64'` (LoongArch - newer Chinese CPU architecture)
   - Complete list: `'arm'`, `'arm64'`, `'ia32'`, `'loong64'`, `'mips'`, `'mipsel'`, `'ppc64'`, `'riscv64'`, `'s390x'`, `'x64'`
   - https://nodejs.org/api/os.html#osarch

7. **`platform()` return type** - Now union of 10 specific platforms instead of generic `string`:
   - `'aix'`, `'android'`, `'darwin'`, `'freebsd'`, `'haiku'`, `'linux'`, `'openbsd'`, `'sunos'`, `'win32'`, `'cygwin'`
   - https://nodejs.org/api/os.html#osplatform

8. **Output type definitions made exact** - Removed spread operators (outputs are mutable)
   - `os$CPU` - Removed spread operators from main type and nested `times` object
   - `os$NetIFAddr` - Added missing `scopeid?` and `cidr` properties, removed spread operator
   - `os$UserInfo$*` - Types are mutable (not readonly) so consumers can modify returned values
   - `networkInterfaces()` return type - Removed spread operator for exact type

9. **Input types use Readonly** - Following readonly rules
   - `userInfo()` options: Changed to `Readonly<{encoding: 'buffer' | 'utf8'}>`
   - Allows passing readonly types safely

**References:**
- Node.js os module docs: https://nodejs.org/api/os.html

Changelog: [Internal]
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Reviewed By: vzaidman

Differential Revision: D89940756

fbshipit-source-id: 29a91c49716bc08eb2c94892e3648db9e40b06d4