fix(ContactsStore): Sanitize user ID given to guest avatar route

It is not allowed to use slashes within path parameters, so they would need to be encoded.
But URL encoded slashes are not suported by Apache, so instead replace slash with space.

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

lib/private/Contacts/ContactsMenu/ContactsStore.php

@@ -353,9 +353,9 @@ class ContactsStore implements IContactsStore {
 				$avatar = $this->urlGenerator->linkToRouteAbsolute('core.avatar.getAvatar', ['userId' => $uid, 'size' => 64]);
 				$entry->setProperty('isUser', true);
 			} elseif (!empty($contact['FN'])) {
-				$avatar = $this->urlGenerator->linkToRouteAbsolute('core.GuestAvatar.getAvatar', ['guestName' => $contact['FN'], 'size' => 64]);
+				$avatar = $this->urlGenerator->linkToRouteAbsolute('core.GuestAvatar.getAvatar', ['guestName' => str_replace('/', ' ', $contact['FN']), 'size' => 64]);
 			} else {
-				$avatar = $this->urlGenerator->linkToRouteAbsolute('core.GuestAvatar.getAvatar', ['guestName' => $uid, 'size' => 64]);
+				$avatar = $this->urlGenerator->linkToRouteAbsolute('core.GuestAvatar.getAvatar', ['guestName' => str_replace('/', ' ', $uid), 'size' => 64]);
 			}
 			$entry->setAvatar($avatar);
 		}