Support for PHP 8 (#2158)

painful 66 commits later: required PHP version bumped to 7.3, plugin updates using migrations necessary!

symfony.lock

@@ -99,9 +99,6 @@
     "doctrine/persistence": {
         "version": "v1.0.0"
     },
-    "doctrine/reflection": {
-        "version": "v1.0.0"
-    },
     "doctrine/sql-formatter": {
         "version": "1.1.1"
     },
@@ -156,9 +153,15 @@
     "illuminate/cache": {
         "version": "v6.0.4"
     },
+    "illuminate/collections": {
+        "version": "v8.44.0"
+    },
     "illuminate/contracts": {
         "version": "v6.0.4"
     },
+    "illuminate/macroable": {
+        "version": "v8.44.0"
+    },
     "illuminate/support": {
         "version": "v6.0.4"
     },
@@ -189,6 +192,9 @@
     "laminas/laminas-code": {
         "version": "3.4.1"
     },
+    "laminas/laminas-escaper": {
+        "version": "2.7.0"
+    },
     "laminas/laminas-eventmanager": {
         "version": "3.2.1"
     },
@@ -267,9 +273,6 @@
     "paragonie/random_compat": {
         "version": "v2.0.17"
     },
-    "pclzip/pclzip": {
-        "version": "2.8.2"
-    },
     "phar-io/manifest": {
         "version": "1.0.1"
     },
@@ -291,9 +294,6 @@
     "phpdocumentor/type-resolver": {
         "version": "0.4.0"
     },
-    "phpoffice/common": {
-        "version": "0.2.9"
-    },
     "phpoffice/phpspreadsheet": {
         "version": "1.4.0"
     },
@@ -816,9 +816,6 @@
     "zendframework/zend-code": {
         "version": "3.3.0"
     },
-    "zendframework/zend-escaper": {
-        "version": "2.6.0"
-    },
     "zendframework/zend-eventmanager": {
         "version": "3.2.0"
     },