build(editorconfig): set max_line_length to 120 only for lua files

Setting it for all filetypes is usually not correct. For example, git
commits are also affected by this option which makes 120 columns too
long.

.editorconfig

@@ -1,13 +1,14 @@
 root = true
 
 [*]
-max_line_length = 120
 indent_style = space
 indent_size = 2
 tab_width = 8
 end_of_line = lf
 insert_final_newline = true
-charset = utf-8
+
+[*.lua]
+max_line_length = 120
 
 [{Makefile,**/Makefile,runtime/doc/*.txt}]
 indent_style = tab