Page Content: Added more complex & configurable content filtering

- Added new option to control parts of the filter.
- Added whitelist filtering pass via HTMLPurifier.

composer.json

@@ -19,6 +19,7 @@
         "ext-zip": "*",
         "bacon/bacon-qr-code": "^3.0",
         "dompdf/dompdf": "^3.1",
+        "ezyang/htmlpurifier": "^4.19",
         "guzzlehttp/guzzle": "^7.4",
         "intervention/image": "^3.5",
         "knplabs/knp-snappy": "^1.5",
@@ -38,7 +39,8 @@
         "socialiteproviders/microsoft-azure": "^5.1",
         "socialiteproviders/okta": "^4.2",
         "socialiteproviders/twitch": "^5.3",
-        "ssddanbrown/htmldiff": "^2.0.0"
+        "ssddanbrown/htmldiff": "^2.0.0",
+        "xemlock/htmlpurifier-html5": "^0.1.12"
     },
     "require-dev": {
         "fakerphp/faker": "^1.21",