Remove lodash from core (#2827)

* Remove `lodash-es` dependency

* Replace `escapeRegExp` with home-made util

* Replace `throttle` with `throttle-debounce` library

* Use native browser methods for `deepFlatten`

We need a polyfill for iOS 11 and below. I think using a native method with this polyfill is better than having our own function instead, even if the bundle size is ~150B more.

* Save a few bytes in `escapeRegExp`

* Fix typo in comment

* Undo import re-organisation

* Use spread instead of slice

* Use smaller Array.flat polyfill from MDN

* Export new utils in `compat.js`

framework/core/js/package.json

@@ -11,16 +11,15 @@
     "expose-loader": "^1.0.3",
     "jquery": "^3.6.0",
     "jquery.hotkeys": "^0.1.0",
-    "lodash-es": "^4.17.21",
     "mithril": "^2.0.4",
     "punycode": "^2.1.1",
     "spin.js": "^3.1.0",
-    "textarea-caret": "^3.1.0"
+    "textarea-caret": "^3.1.0",
+    "throttle-debounce": "^3.0.1"
   },
   "devDependencies": {
     "@babel/preset-typescript": "^7.13.0",
     "@types/jquery": "^3.5.5",
-    "@types/lodash-es": "^4.17.4",
     "@types/mithril": "^2.0.7",
     "@types/punycode": "^2.1.0",
     "@types/textarea-caret": "^3.0.0",