When creating sharePendingIntent use a unique requestCode so a new PendingIntent is created

Summary:
Fixes the situation where when 2 or more files are send to Android clicking the share button
in either of the notifications will always share the last received file.

BUG: 396051

Test Plan:
Send 2 files to android
Click on the share button of the first received file

The first file is actually used for the share and not the last received file

Reviewers: KDE Connect, albertvaka

Reviewed By: KDE Connect, albertvaka

Subscribers: albertvaka, kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D16707