fix(shim): fix a minor issue with Get-Subsystem (and refactor)

[spider2048]

Description

Fixes minor bugs

Motivation and Context

The Get-Subsystem function doesn't catch errors when it fails to read a binary.
The Get-Subsystem and Change-Subsystem functions are refactored to Get-PESubsystem and Change-PESubsystem.
The code will only try to change subsystem to 2 (which indicates GUI)

Relates to #5559

How Has This Been Tested?

Credits to @HUMORCE (original).

Steps to reproduce the bug:

% touch empty.exe
% scoop shim add empty .\empty.exe
Adding local shim empty...
MethodInvocationException: D:\Sources\Scoop\lib\core.ps1:12
Line |
  12 |          $peOffset = $binaryReader.ReadInt32()
     |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     | Exception calling "ReadInt32" with "0" argument(s): "Unable to read beyond the end of the stream."

Checklist:

• I have read the Contributing Guide.
• I have ensured that I am targeting the develop branch.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.
• I have added an entry in the CHANGELOG.

[rashil2000]

There should be a catch block in the Change-PESubsystem function too, right, just in case?

[r15ch13]

And use a approved PowerShell verb by changing Change-PESubsystem to Set-PESubsystem

[spider2048]

I've refactored Change-PESubsystem to Set-PESubsystem and added an additional catch block as requested.
I think it is good to go.