Make Omnistudio local compiler optional

External users may not have access to the Vlocity private NPM
repository, blocking them from installing front end dependencies. This
change allows yarn install to complete successfully.

package.json

@@ -52,7 +52,6 @@
     "heroku-postbuild": "yarn prod"
   },
   "dependencies": {
-    "@omnistudio/omniscript-lwc-compiler": "^244.4.0",
     "@react-hook/window-scroll": "^1.3.0",
     "@salesforce-ux/design-system": "^2.18.1",
     "@salesforce/design-system-react": "^0.10.48",
@@ -154,6 +153,9 @@
     "webpack-dev-server": "^4.9.3",
     "webpack-merge": "^5.8.0"
   },
+  "optionalDependencies": {
+    "@omnistudio/omniscript-lwc-compiler": "^244.4.0"
+  },
   "resolutions": {
     "@storybook/**/ansi-regex": "^5.0.1",
     "@storybook/**/glob-parent": "^5.1.2",