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/immich-openapi-specs.json

@@ -8061,6 +8061,9 @@
           "job": {
             "$ref": "#/components/schemas/SystemConfigJobDto"
           },
+          "library": {
+            "$ref": "#/components/schemas/SystemConfigLibraryDto"
+          },
           "machineLearning": {
             "$ref": "#/components/schemas/SystemConfigMachineLearningDto"
           },
@@ -8104,7 +8107,8 @@
           "job",
           "thumbnail",
           "trash",
-          "theme"
+          "theme",
+          "library"
         ],
         "type": "object"
       },
@@ -8238,6 +8242,32 @@
         ],
         "type": "object"
       },
+      "SystemConfigLibraryDto": {
+        "properties": {
+          "scan": {
+            "$ref": "#/components/schemas/SystemConfigLibraryScanDto"
+          }
+        },
+        "required": [
+          "scan"
+        ],
+        "type": "object"
+      },
+      "SystemConfigLibraryScanDto": {
+        "properties": {
+          "cronExpression": {
+            "type": "string"
+          },
+          "enabled": {
+            "type": "boolean"
+          }
+        },
+        "required": [
+          "enabled",
+          "cronExpression"
+        ],
+        "type": "object"
+      },
       "SystemConfigMachineLearningDto": {
         "properties": {
           "classification": {