feat(server,web): system config for admin (#959)

* feat: add admin config module for user configured config, uses it for ffmpeg

* feat: add api endpoint to retrieve admin config settings and values

* feat: add settings panel to admin page on web (wip)

* feat: add api endpoint to update the admin config

* chore: re-generate openapi spec after rebase

* refactor: move from admin config to system config naming

* chore: move away from UseGuards to new @Authenticated decorator

* style: dark mode styling for lists and fix conflicting colors

* wip: 2 column design, no edit button

* refactor: system config

* chore: generate open api

* chore: rm broken test

* chore: cleanup types

* refactor: config module names

Co-authored-by: Zack Pollard <zackpollard@ymail.com>
Co-authored-by: Zack Pollard <zack.pollard@moonpig.com>

mobile/openapi/lib/model/system_config_response_item.dart

@@ -0,0 +1,135 @@
+//
+// AUTO-GENERATED FILE, DO NOT MODIFY!
+//
+// @dart=2.12
+
+// ignore_for_file: unused_element, unused_import
+// ignore_for_file: always_put_required_named_parameters_first
+// ignore_for_file: constant_identifier_names
+// ignore_for_file: lines_longer_than_80_chars
+
+part of openapi.api;
+
+class SystemConfigResponseItem {
+  /// Returns a new [SystemConfigResponseItem] instance.
+  SystemConfigResponseItem({
+    required this.name,
+    required this.key,
+    required this.value,
+    required this.defaultValue,
+  });
+
+  String name;
+
+  SystemConfigKey key;
+
+  String value;
+
+  String defaultValue;
+
+  @override
+  bool operator ==(Object other) => identical(this, other) || other is SystemConfigResponseItem &&
+     other.name == name &&
+     other.key == key &&
+     other.value == value &&
+     other.defaultValue == defaultValue;
+
+  @override
+  int get hashCode =>
+    // ignore: unnecessary_parenthesis
+    (name.hashCode) +
+    (key.hashCode) +
+    (value.hashCode) +
+    (defaultValue.hashCode);
+
+  @override
+  String toString() => 'SystemConfigResponseItem[name=$name, key=$key, value=$value, defaultValue=$defaultValue]';
+
+  Map<String, dynamic> toJson() {
+    final _json = <String, dynamic>{};
+      _json[r'name'] = name;
+      _json[r'key'] = key;
+      _json[r'value'] = value;
+      _json[r'defaultValue'] = defaultValue;
+    return _json;
+  }
+
+  /// Returns a new [SystemConfigResponseItem] instance and imports its values from
+  /// [value] if it's a [Map], null otherwise.
+  // ignore: prefer_constructors_over_static_methods
+  static SystemConfigResponseItem? fromJson(dynamic value) {
+    if (value is Map) {
+      final json = value.cast<String, dynamic>();
+
+      // Ensure that the map contains the required keys.
+      // Note 1: the values aren't checked for validity beyond being non-null.
+      // Note 2: this code is stripped in release mode!
+      assert(() {
+        requiredKeys.forEach((key) {
+          assert(json.containsKey(key), 'Required key "SystemConfigResponseItem[$key]" is missing from JSON.');
+          assert(json[key] != null, 'Required key "SystemConfigResponseItem[$key]" has a null value in JSON.');
+        });
+        return true;
+      }());
+
+      return SystemConfigResponseItem(
+        name: mapValueOfType<String>(json, r'name')!,
+        key: SystemConfigKey.fromJson(json[r'key'])!,
+        value: mapValueOfType<String>(json, r'value')!,
+        defaultValue: mapValueOfType<String>(json, r'defaultValue')!,
+      );
+    }
+    return null;
+  }
+
+  static List<SystemConfigResponseItem>? listFromJson(dynamic json, {bool growable = false,}) {
+    final result = <SystemConfigResponseItem>[];
+    if (json is List && json.isNotEmpty) {
+      for (final row in json) {
+        final value = SystemConfigResponseItem.fromJson(row);
+        if (value != null) {
+          result.add(value);
+        }
+      }
+    }
+    return result.toList(growable: growable);
+  }
+
+  static Map<String, SystemConfigResponseItem> mapFromJson(dynamic json) {
+    final map = <String, SystemConfigResponseItem>{};
+    if (json is Map && json.isNotEmpty) {
+      json = json.cast<String, dynamic>(); // ignore: parameter_assignments
+      for (final entry in json.entries) {
+        final value = SystemConfigResponseItem.fromJson(entry.value);
+        if (value != null) {
+          map[entry.key] = value;
+        }
+      }
+    }
+    return map;
+  }
+
+  // maps a json object with a list of SystemConfigResponseItem-objects as value to a dart map
+  static Map<String, List<SystemConfigResponseItem>> mapListFromJson(dynamic json, {bool growable = false,}) {
+    final map = <String, List<SystemConfigResponseItem>>{};
+    if (json is Map && json.isNotEmpty) {
+      json = json.cast<String, dynamic>(); // ignore: parameter_assignments
+      for (final entry in json.entries) {
+        final value = SystemConfigResponseItem.listFromJson(entry.value, growable: growable,);
+        if (value != null) {
+          map[entry.key] = value;
+        }
+      }
+    }
+    return map;
+  }
+
+  /// The list of required keys that must be present in a JSON.
+  static const requiredKeys = <String>{
+    'name',
+    'key',
+    'value',
+    'defaultValue',
+  };
+}
+