editorconfig: Declare max line lengths for JS/Python code.

110 is what we enforce in Python code via our existing lint rules, and
120 is what we'd most realistically move the JS codebase to next.

Make supported IDEs and text editors keep a maximum line length of 110
characters for most code files.

.editorconfig

@@ -10,6 +10,12 @@ insert_final_newline = true
 indent_style = space
 indent_size = 4
 
+[*.{py}]
+max_line_length = 110
+
+[*.{js}]
+max_line_length = 120
+
 [*.{svg,rb,pp,pl}]
 indent_style = space
 indent_size = 2