Added get admins command to list SCCM admin users

[Mayyhem]

Description

Added get admins command to list SCCM admin users

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Testing

SharpSCCM.exe get admins -sms localhost -sc cas

Bonus Points:

• I have commented my code, particularly in hard-to-understand areas
• I have incremented the build/revision number in https://github.com/Mayyhem/SharpSCCM/blob/main/Properties/AssemblyInfo.cs
• I have made corresponding changes to the Wiki and RELEASE_NOTES.md
• I have added unit tests that prove my fix is effective or that my feature works