fix(scoop-update): Enforce $null array

[niheaven]

Description

Hotfix for #4720

If Get-Dependency() output $null, (Get-Dependency $app $architecture) -ne $app gives $false while @(Get-Dependency $app $architecture) -ne $app gives $null which is needed to ensure_none_failed()

Also some small fixes.

Motivation and Context

Relates to #4720

How Has This Been Tested?

Before:

After:

Checklist:

• I have read the Contributing Guide.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.