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>

server/src/domain/domain.util.ts

@@ -1,6 +1,7 @@
 import { applyDecorators } from '@nestjs/common';
 import { ApiProperty } from '@nestjs/swagger';
 import { IsArray, IsNotEmpty, IsOptional, IsString, IsUUID, ValidateIf, ValidationOptions } from 'class-validator';
+import { CronJob } from 'cron';
 import { basename, extname } from 'node:path';
 import sanitize from 'sanitize-filename';
 
@@ -18,6 +19,16 @@ export function ValidateUUID({ optional, each }: Options = { optional: false, ea
   );
 }
 
+export function validateCronExpression(expression: string) {
+  try {
+    new CronJob(expression, () => {});
+  } catch (error) {
+    return false;
+  }
+
+  return true;
+}
+
 interface IValue {
   value?: string;
 }