SetupAssist should check for CustomSD

Setup may fail like so:

[12/05/2022 12:22:06.0909] [1] Ending processing Start-PreFileCopy
[12/05/2022 12:22:06.0914] [0] The log file path for the language pack removal operation is set to 'C:\ExchangeSetupLogs'.
[12/05/2022 12:22:06.0924] [0] [WARNING] Exception has been thrown by the target of an invocation.
[12/05/2022 12:22:06.0939] [0] [WARNING] Cannot open log for source 'MSExchangeSetup'. You may not have write access.
[12/05/2022 12:22:06.0939] [0] [WARNING] Access is denied
[12/05/2022 12:22:06.0939] [0] CurrentResult SetupLauncherHelper.loadassembly:444: 1
[12/05/2022 12:22:06.0939] [0] The Exchange Server setup operation didn't complete.  More details can be found in ExchangeSetup.log located in the <SystemDrive>:\ExchangeSetupLogs folder.
[12/05/2022 12:22:06.0939] [0] CurrentResult main.run:235: 1
[12/05/2022 12:22:06.0939] [0] CurrentResult setupbase.maincore:396: 1
[12/05/2022 12:22:06.0939] [0] End of Setup
[12/05/2022 12:22:06.0939] [0] **********************************************

See: https://learn.microsoft.com/en-us/exchange/error-message-when-upgrading-cumulative-updates?view=exchserver-2019#error-message-when-upgrading-cumulative-updates-in-exchange

This can occur if the CustomSD value exists. See:

https://learn.microsoft.com/en-us/windows/win32/eventlog/eventlog-key
https://learn.microsoft.com/en-us/windows/win32/eventlog/event-logging-security

In the doc it describes a situation where BA (built-in administrators) has been granted too few rights. However, there are many ways that this SD could deny access to the user running setup.

Likely the best approach here would be to look for this failure text in the setup log, and if present, check for the existence of CustomSD, and if it's there, call it out as a potential issue.