Reduce dependency on Invoke-Expression to improve security

[arudell]

Description

This pull request refactors several PowerShell scripts to remove the use of Invoke-Expression when executing system commands, replacing it with direct invocation using the call operator (&). This change enhances security, reliability, and readability by avoiding unnecessary command parsing and potential injection risks. Additionally, a minor change in the test initialization script simplifies how configuration data is loaded.

PowerShell command execution refactoring:

• Replaced Invoke-Expression with the call operator (&) for starting, updating, and stopping ETW trace sessions in Start-EtwTraceSession and Stop-EtwTraceSession functions in src/modules/SdnDiag.Common.psm1. [1] [2] [3]
• Updated Disable-SdnRasGatewayTracing and Enable-SdnRasGatewayTracing in src/modules/SdnDiag.Gateway.psm1 to use the call operator for netsh commands. [1] [2]
• Modified Get-OvsdbDatabase, Get-ServerConfigState, and Test-SdnVfpPortTuple in src/modules/SdnDiag.Server.psm1 to use the call operator for their respective command-line tools. [1] [2] [3]

Test script simplification:

• In tests/online/RunTests.ps1, removed Invoke-Expression from the loading of configuration data, directly assigning the output of Get-Content to the configuration hashtable.

Change type

• Bug fix (non-breaking change)
• Code style update (formatting, local variables)
• New Feature (non-breaking change that adds new functionality without impacting existing)
• Breaking change (fix or feature that may cause functionality impact)
• Other

Checklist:

• My code follows the style and contribution guidelines of this project.
• I have tested and validated my code changes.