eliminate duplication of JetBrains rules in VisualStudio

Global/JetBrains.gitignore

@@ -47,3 +47,6 @@ fabric.properties
 
 # Editor-based Rest Client
 .idea/httpRequests
+
+# Rider-specific rules
+*.sln.iml

VisualStudio.gitignore

@@ -286,10 +286,6 @@ paket-files/
 # FAKE - F# Make
 .fake/
 
-# JetBrains Rider
-.idea/
-*.sln.iml
-
 # CodeRush
 .cr/