feat: unicorn/prefer-trim-start-end for node

In preparation for requiring node >= 10, which supports
String#trimStart/trimEnd, prefer these functions in the node
environment.  Leave disabled on other environments until supported by
Firefox LTS.

BREAKING CHANGE: Enable unicorn/prefer-trim-start-end for the node
environment.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>

node.js

@@ -25,6 +25,9 @@ module.exports = {
 
     // don't require .flatMap() over .map().flat()
     // since .flatMap() only became available in Node 11
-    "unicorn/prefer-flat-map": "off"
+    "unicorn/prefer-flat-map": "off",
+
+    // prefer String#trimStart/trimEnd to trimLeft/trimRight
+    "unicorn/prefer-trim-start-end": "error"
   }
 };

rules/unicorn.js

@@ -73,8 +73,8 @@ module.exports = {
     // these have different behavior and uses
     "unicorn/prefer-text-content": "off",
 
-    // trimStart/trimEnd are not always available in supported environments
-    // TODO [engine:node@>=10]: enable for Node, consider for other environments
+    // don't prefer trimStart/trimEnd to trimLeft/trimRight
+    // TODO: enable once supported by Firefox ESR
     "unicorn/prefer-trim-start-end": "off",
 
     // don't prevent common abbreviations