Fix parameter preparation for occ command

[R0Wi]

• Fix for [bug] Issue when trying to install external app via appstore #517
• Filters empty occ commandline params
• Adds improved logging in case this ever happens again (it was pretty hard to find the bug because after the occ command has been sent, nothing could be found in the logs)

Notes

• I was only able to reproduce this on NC31 (because I didn't find any NC32 compatible apps in the store, yet). So the base for this fix is stable31
• I took the liberty of defaulting $this->config->getSystemValue('apps_paths') with [], because I found some errors in my logs when trying to uninstall an app (something like "foreach needs an array, string given ..."). This happens if app_paths is not set. getSystemValue will return an "empty" string in that case.
• If possible, a testcase should be added for this. Maybe with any deployed app which is updated regularly? Note that the problem did not occur when doing the "test install"

[oleksandr-nc]

Was on vacation, sorry for the delay in replying.

And why is PR made in stable31 branch? Maybe it would be better to make it in main and backport it?

[oleksandr-nc]

@R0Wi good time of day. Are you willing to rebase this PR on main branch or should we do it ourselves?

[R0Wi]

Hi @oleksandr-nc, sorry for the delayed answer. Unfortunately I've been out sick last week.

Happy to incorporate your review findings tonight 👍

[R0Wi]

@oleksandr-nc rebased on main and incorporated your feedback. Needs to be backported to stable31 ...

[oleksandr-nc]

/backport to stable31

[oleksandr-nc]

@oleksandr-nc rebased on main and incorporated your feedback. Needs to be backported to stable31 ...

Thank you