feat(ext/node): add MIMEType, convertProcessSignalToExitCode, Symbol.dispose for ChildProcess (#32793)
- Implements util.MIMEType and util.MIMEParams classes (Node.js v18.13+)
with full MIME type parsing and serialization
- Adds util.convertProcessSignalToExitCode() to convert signal names to
exit codes (128 + signal number)
- Adds ChildProcess[Symbol.dispose]() support for explicit resource
management
- Adds ERR_INVALID_MIME_SYNTAX error code
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>