Enable the ESLint prefer-spread rule

Note that in a couple of spots the argument could be `undefined` and there we simply disable the rule instead.

Please refer to https://eslint.org/docs/latest/rules/prefer-spread

src/core/evaluator.js

@@ -3717,7 +3717,7 @@ class PartialEvaluator {
               const w2 = (token.charCodeAt(k) << 8) | token.charCodeAt(k + 1);
               str.push(((w1 & 0x3ff) << 10) + (w2 & 0x3ff) + 0x10000);
             }
-            map[charCode] = String.fromCodePoint.apply(String, str);
+            map[charCode] = String.fromCodePoint(...str);
           });
           return new ToUnicodeMap(map);
         },