(maint) Add vscode settings file

To add a setting to ensure that UTF-8 with BOM is used for PowerShell
files,

Author: gep13

.gitignore

@@ -5,7 +5,8 @@ code_drop
 [Bb]in
 obj
 src/packages
-/.vscode/
+/.vscode/**
+!/.vscode/settings.json
 .vs
 
 *.suo

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "[powershell]": {
+        "files.encoding": "utf8bom",
+    }
+}