NFC: Create .editorconfig (#2125)

This sets formatting preferences automatically for editors that support this config file.

Author: MaxDesiatov

.editorconfig

@@ -0,0 +1,10 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true
+insert_final_newline = true
+xcode_trim_whitespace_on_empty_lines = true