Update generate-wine-glass to use an output buffer

[N6UDP]

This increases performance on my machine from about 2 minutes to 1.5 seconds as measured by measure-command.
https://github.com/dlwyatt/PowershellProfiler shows almost all the time was in the IO from Add-Content:

File                      Line HitCount PercentHitCount TotalMilliseconds PercentTime
----                     ---- -------- --------------- ----------------- -----------
generate-wine-glass.ps1  102     6480            3.13             39244       29.84
generate-wine-glass.ps1   99     6480            3.13             39044       29.69
generate-wine-glass.ps1  112     6240            3.02             37490       28.51