chore(all): update editorconfig for rust files (#17111)

Ensure the indentation for rust files is 4 spaces.

This shouldn't cause any problems for oxfmt and also won't make my
editor try to use 2 spaces for rust code :)

.editorconfig

@@ -8,3 +8,6 @@ end_of_line = lf
 insert_final_newline = true
 indent_style = space
 indent_size = 2
+
+[*.rs]
+indent_size = 4