mxc-sdk: diagnostic.js runs a PATH-resolved `whoami` at import time, even with diagnostics off

[Ninozzz95]

Package: @microsoft/mxc-sdk 0.8.0, dist/diagnostic.js.

What happens
At module load, diagnostic.js computes PIPE_NAME by calling getDiagnosticPipeName(). On Windows this runs
execSync('whoami /user /fo csv /nh', …). It runs on every import, whether or not the diagnostic console is enabled.
execSync goes through the shell, so whoami is resolved from PATH.

Why it matters

1. On machines where another whoami comes before System32 in PATH, that program runs instead. Git for Windows'
   usr/bin is a common case. It prints whoami: extra operand '/user' on the host process's stderr. In a full-screen
   terminal application that text lands on top of the UI.
2. Any executable named whoami found earlier in PATH runs at import time with the host's rights, even though the
   caller never enabled diagnostics.

Suggested fix (any of these)

• Compute the pipe name lazily, only when the diagnostic console is enabled.
• Run %SystemRoot%\System32\whoami.exe by absolute path with execFileSync (no shell).
• Obtain the SID without spawning a process.

Repro
On Windows, put Git for Windows' usr\bin before System32 in PATH, then import the package, for example with
node --input-type=module -e "await import('@microsoft/mxc-sdk')". The whoami error appears on stderr.