Add support to pinia (vuejs#1675)

Author: Luiz Otávio Carvalho

lib/rules/no-unused-properties.js

@@ -496,12 +496,16 @@ module.exports = {
           let groupName = null
           if (/^mapMutations|mapActions$/u.test(node.callee.name)) {
             groupName = 'methods'
-          } else if (/^mapState|mapGetters$/u.test(node.callee.name)) {
+          } else if (
+            /^mapState|mapGetters|mapWritableState$/u.test(node.callee.name)
+          ) {
             groupName = 'computed'
           }
 
           if (!groupName || node.arguments.length === 0) return
-          const arg = node.arguments[0]
+          // On Pinia the store is always the first argument
+          const arg =
+            node.arguments.length === 2 ? node.arguments[1] : node.arguments[0]
           if (arg.type === 'ObjectExpression') {
             // e.g.
             // `mapMutations({ add: 'increment' })`