Detect processes preventing updates

[dlon]

Detect which processes are preventing the (un)installer from deleting the app directory during updates, and ask the user to close them.

It suffers from an annoying limitation, namely that the message will be shown up to five times if the uninstaller fails. This is mentioned as a limitation in the script for now.

Fix DES-2208

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This change is 

[linear[bot]]

DES-2208 Handle uninstallation when other processes has file handles on app folder

[hulthe]

:pog: