chore(server): Store generated files (thumbnails, encoded video) in subdirectories (#4112)

* save thumbnails in subdirectories

* migration job, migrate assets and face thumbnails

* fix tests

* directory depth of two instead of three

* cleanup empty dirs after migration

* clean up empty dirs after migration, migrate people without assetId

* add job card for new migration job

* fix removeEmptyDirs race condition because of missing await

* cleanup empty directories after asset deletion

* move ensurePath to storage core

* rename jobs

* remove unnecessary property of IEntityJob

* use updated person getById, minor refactoring

* ensure that directory cleanup doesn't interfere with migration

* better description for job in ui

* fix remove directories when migration is done

* cleanup empty folders at start of migration

* fix: actually persist concurrency setting

* add comment explaining regex

* chore: cleanup

---------

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

web/src/lib/components/admin-page/jobs/jobs-panel.svelte

@@ -110,6 +110,12 @@
       allowForceCommand: false,
       component: StorageMigrationDescription,
     },
+    [JobName.Migration]: {
+      icon: FolderMove,
+      title: api.getJobName(JobName.Migration),
+      subtitle: 'Migrate thumbnails for assets and faces to the latest folder structure',
+      allowForceCommand: false,
+    },
   };
   $: jobList = Object.entries(jobDetails) as [JobName, JobDetails][];