chore: Add .editorconfig to enforce consistent styling (#12021)

Github respects editorconfig settings. Adding indent_size as 4 in
settings makes github indent code to 4 columns.

.editorconfig

@@ -0,0 +1,14 @@
+# Root editor config file
+root = true
+
+# Common settings
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8
+
+# python, js indentation settings
+[{*.py,*.js}]
+indent_style = tab
+indent_size = 4