fix: optimize bin/npm

[darcyclarke]

Summary

Today, running npm can cause us to boot node twice to determine the npm prefix value & this can be prohibitively expensive on platforms like Windows

Exit Criteria

• investigate opportunities for optimizations & potentially use node by default using child_process.fork
• refactor bin/npm

Links & References

• bin/npm script: https://github.com/npm/cli/blob/latest/bin/npm

[wraithgar]

npm/cli#7271