refactor: include Rider files (#1201)

According to [JetBrains](https://github.com/JetBrains/resharper-rider-samples/blob/master/.gitignore) some files in the `.idea` directory should not be excluded.

Author: vbreuss

.gitignore

@@ -152,9 +152,30 @@ $RECYCLE.BIN/
 # Mac crap
 .DS_Store
 
-# JetBrains Rider IDE files
-.idea/
-
 #System.IO.Abstractions specific ignores
 Releases
 System.IO.Abstractions.*.nupkg
+
+# Common IntelliJ Platform excludes
+# https://github.com/JetBrains/resharper-rider-samples/blob/master/.gitignore
+
+# User specific
+**/.idea/**/workspace.xml
+**/.idea/**/tasks.xml
+**/.idea/shelf/*
+**/.idea/dictionaries
+**/.idea/httpRequests/
+
+# Sensitive or high-churn files
+**/.idea/**/dataSources/
+**/.idea/**/dataSources.ids
+**/.idea/**/dataSources.xml
+**/.idea/**/dataSources.local.xml
+**/.idea/**/sqlDataSources.xml
+**/.idea/**/dynamic.xml
+
+# Rider
+# Rider auto-generates .iml files, and contentModel.xml
+**/.idea/**/*.iml
+**/.idea/**/contentModel.xml
+**/.idea/**/modules.xml

.idea/.idea.System.IO.Abstractions/.idea/.gitignore

@@ -29,6 +29,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "_", "_", "{BBF7AD8D-5522-48
 		README.md = README.md
 		version.json = version.json
 		Directory.Packages.props = Directory.Packages.props
+		.gitignore = .gitignore
 	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".github", ".github", "{2BE9161B-A3F3-4511-81DB-DB1DCB6375C9}"