Add multiple file/directory deletion in the filemanager (#544)

* Add deletion of multiple selected files
* Adjust success/failure text to properly represent multiple files
* Actually update the minimized versions with the new code
* Use let instead of var and seperate items into seperate code tags
* Deleting the selected items now supports the new endpoint
* Replaced the select buttons with checkboxes
* Selections is now handled by find all the selected checkboxes
* Add a warning if no files/folders are selected when pressing delete
* Add a select all files/folders checkbox
* Move mass delete button into a mass actions dropdown
* Move style to css file
* Actually update the minimized files (again)
* Mass actions button is now disabled by default
* Clicking on a row selects the checkbox and enables the actions button
* Fix clicking anything else but the row or checkbox triggering selection

resources/lang/en/server.php

@@ -213,6 +213,8 @@ return [
         'last_modified' => 'Last Modified',
         'add_new' => 'Add New File',
         'add_folder' => 'Add New Folder',
+        'mass_actions' => 'Mass actions',
+        'delete' => 'Delete',
         'edit' => [
             'header' => 'Edit File',
             'header_sub' => 'Make modifications to a file from the web.',