Fix release-it config

- Move the deps to the root of the repo.
- Switch to the new plugin system.
- Add the workspaces plugin.
- Configure each package appropriately.

Author: chriskrycho

addon/package.json

@@ -43,21 +43,6 @@
   "ember": {
     "edition": "octane"
   },
-  "release-it": {
-    "plugins": {
-      "release-it-lerna-changelog": {
-        "infile": "CHANGELOG.md",
-        "launchEditor": true
-      }
-    },
-    "git": {
-      "tagName": "v${version}"
-    },
-    "github": {
-      "release": true,
-      "tokenRef": "GITHUB_AUTH"
-    }
-  },
   "volta": {
     "extends": "../package.json"
   }