PR Summary

Bounds long string values included in member invocation logging while preserving the method invocation and recording the original string length.

PR Context

Addresses #21473.

MemberInvocationLoggingOps.ArgumentToString() currently returns full string arguments, so LogMemberInvocation() can build very large AMSI report content for calls such as FromBase64String with large strings. This change keeps short strings unchanged, truncates long strings to 4096 characters, and appends a marker with the original length. It also applies the same bound to special primitive-like ToString() results, such as very large BigInteger values.

PR Checklist

• PR has a meaningful title
• Summarized changes
• This PR is focused on one issue
• Make sure all .h, .cpp, .cs, .ps1 and .psm1 files have the correct copyright header
• This PR is ready to merge and is not work-in-progress
• Breaking change: No
• User-facing change: Not required
• Tests added/updated

Validation

• Start-PSBuild -Clean -PSModuleRestore -UseNuGetOrg built pwsh.exe. The first local build surfaced analyzer CA1845 for string construction; the patch was updated to use span-based string.Concat. The follow-up build produced pwsh.exe; the Windows PowerShell 5.1 build wrapper emitted post-build ConvertFrom-Json -Depth compatibility warnings after build output was produced.
• Start-PSPester -Path test/powershell/engine/Logging/MemberInvocationLogging.Tests.ps1 -UseNuGetOrg -ThrowOnFailure -Terse -SkipTestToolBuild passed: 2 passed, 0 failed.