runelite-client: add methods for externals (plugin-hub) (#2286)

* Merge pull request #/10524 from Trevor159/get-var

Add getVar methods for external plugins

* Add the mixins

* fix dumb yaml error

recommend https://yaml-online-parser.appspot.com/

Co-authored-by: Adam <adam@sigterm.info>

.github/workflows/scraper.yml

@@ -13,7 +13,7 @@ jobs:
         with:
           repository: open-osrs/runelite
           ref: master
-        -
+
       - uses: actions/checkout@v1
         with:
           repository: open-osrs/cache-client