feat: add .editorconfig

.editorconfig

@@ -0,0 +1,20 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.cs]
+indent_size = 4
+
+[*.sln]
+charset = utf-8-bom
+end_of_line = crlf
+indent_style = tab