[MM-59552] Remove unsafe-inline from internal CSP, replace with nonce and rework some dynamic styling (#3120)

* Remove unsafe-inline

* Fix dynamic dark mode loading

* Include nonce generator for CSP for styles

* Add nonce provider for react-select

* Fix test

package.json

@@ -159,6 +159,7 @@
     "webpack-merge": "5.8.0"
   },
   "dependencies": {
+    "@emotion/react": "11.11.4",
     "@mattermost/compass-icons": "0.1.45",
     "auto-launch": "5.0.6",
     "bootstrap": "4.6.1",