feat(server): custom library scanning interval (#4390)

* add automatic library scan config options

* add validation

* open api

* use CronJob instead of cron-validator

* fix tests

* catch potential error of the library scan initialization

* better description for input field

* move library scan job initialization to server app service

* fix tests

* add comments to all parameters of cronjob contructor

* make scan a child of a more general library object

* open api

* chore: cleanup

* move cronjob handling to job repoistory

* web: select for common cron expressions

* fix open api

* fix tests

* put scanning settings in nested accordion

* fix system config validation

* refactor, tests

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

mobile/openapi/lib/model/system_config_library_dto.dart

@@ -0,0 +1,98 @@
+//
+// 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 SystemConfigLibraryDto {
+  /// Returns a new [SystemConfigLibraryDto] instance.
+  SystemConfigLibraryDto({
+    required this.scan,
+  });
+
+  SystemConfigLibraryScanDto scan;
+
+  @override
+  bool operator ==(Object other) => identical(this, other) || other is SystemConfigLibraryDto &&
+     other.scan == scan;
+
+  @override
+  int get hashCode =>
+    // ignore: unnecessary_parenthesis
+    (scan.hashCode);
+
+  @override
+  String toString() => 'SystemConfigLibraryDto[scan=$scan]';
+
+  Map<String, dynamic> toJson() {
+    final json = <String, dynamic>{};
+      json[r'scan'] = this.scan;
+    return json;
+  }
+
+  /// Returns a new [SystemConfigLibraryDto] instance and imports its values from
+  /// [value] if it's a [Map], null otherwise.
+  // ignore: prefer_constructors_over_static_methods
+  static SystemConfigLibraryDto? fromJson(dynamic value) {
+    if (value is Map) {
+      final json = value.cast<String, dynamic>();
+
+      return SystemConfigLibraryDto(
+        scan: SystemConfigLibraryScanDto.fromJson(json[r'scan'])!,
+      );
+    }
+    return null;
+  }
+
+  static List<SystemConfigLibraryDto> listFromJson(dynamic json, {bool growable = false,}) {
+    final result = <SystemConfigLibraryDto>[];
+    if (json is List && json.isNotEmpty) {
+      for (final row in json) {
+        final value = SystemConfigLibraryDto.fromJson(row);
+        if (value != null) {
+          result.add(value);
+        }
+      }
+    }
+    return result.toList(growable: growable);
+  }
+
+  static Map<String, SystemConfigLibraryDto> mapFromJson(dynamic json) {
+    final map = <String, SystemConfigLibraryDto>{};
+    if (json is Map && json.isNotEmpty) {
+      json = json.cast<String, dynamic>(); // ignore: parameter_assignments
+      for (final entry in json.entries) {
+        final value = SystemConfigLibraryDto.fromJson(entry.value);
+        if (value != null) {
+          map[entry.key] = value;
+        }
+      }
+    }
+    return map;
+  }
+
+  // maps a json object with a list of SystemConfigLibraryDto-objects as value to a dart map
+  static Map<String, List<SystemConfigLibraryDto>> mapListFromJson(dynamic json, {bool growable = false,}) {
+    final map = <String, List<SystemConfigLibraryDto>>{};
+    if (json is Map && json.isNotEmpty) {
+      // ignore: parameter_assignments
+      json = json.cast<String, dynamic>();
+      for (final entry in json.entries) {
+        map[entry.key] = SystemConfigLibraryDto.listFromJson(entry.value, growable: growable,);
+      }
+    }
+    return map;
+  }
+
+  /// The list of required keys that must be present in a JSON.
+  static const requiredKeys = <String>{
+    'scan',
+  };
+}
+