Support validation for multiple aliases in a single portable executable

Brief description of your issue

winget validate fails locally for nested portable executables with multiple aliases. Some applications expect multiple aliases from one command, which is why this is important.

Related to https://github.com/microsoft/winget-cli/issues/2523#issue-1376643992:

• This might be acceptable as long as they have different command aliases?

Perhaps this was overlooked.

Steps to reproduce

1. Checkout https://github.com/microsoft/winget-pkgs/pull/94699
2. Validate the Fly-io.flyctl manifest locally with winget validate
3. Validation fails with this error:

Manifest validation failed.
Manifest Error: Duplicate relative file path found. [RelativeFilePath]
Manifest Error: Duplicate relative file path found. [RelativeFilePath]

Installation works as intended however, creating fly and flyctl aliases for flyctl.exe.

Expected behavior

Validation should succeed

Actual behavior

Validation is failing.

Environment

Windows: Windows.Desktop v10.0.22621.1105
System Architecture: X64
Package: Microsoft.DesktopAppInstaller v1.19.10173.0

Reproduce the failure by validating the Fly-io.flyctl manifest from winget-pkgs pull request 94699 with winget validate. Trace manifest validation for nested portable executables and duplicate relative file paths when multiple aliases target one executable. Done means validation succeeds while installation continues to create both fly and flyctl aliases.