fix: protect spam folder name

- Enclose the spam folder name in double quotes, to allow the usage of the
  space character.
- Forbid double quotes character in spam folder name.

Author: DavidePrincipi

dovecot/usr/local/lib/templates/local.conf

@@ -49,11 +49,11 @@ last_valid_gid = 101
 
 namespace inbox {
   separator = /
-  mailbox ${tmpl_spam_folder} {
+  mailbox "${tmpl_spam_folder}" {
     special_use = \Junk
     auto = ${tmpl_spam_folder_auto}
   }
-  mailbox ${tmpl_trash_folder} {
+  mailbox "${tmpl_trash_folder}" {
     special_use = \Trash
     auto = subscribe
   }

imageroot/validator-definitions.json

@@ -458,7 +458,8 @@
                 "name": {
                     "type": "string",
                     "title": "Folder name",
-                    "minLength": 1
+                    "minLength": 1,
+                    "pattern": "^[^\"]+$"
                 }
             }
         },