Drop underscores from repo folder names

[guardrex]

cc: @wadepickett @tdykstra

There are ~274 total _static folders with about 29 of them in the Blazor node.

I should be able to automate this task fairly easily. A good time for it will be perhaps the holiday season 🎄when there might just be a small number of open PRs ... i.e., minimal merge conflict chances. I'll make sure that I look at the other underscore-named folders as well for this work.

I'll take a shot at this EOY.