[New Feature]: Remove Legacy Installer Version for Portable Package

[DanTheMan827]

Description of the new feature/enhancement

I have an application that ships with both an installer and a portable version. For WinGet distribution, I would prefer to use the portable package as it's a CLI-based tool.

However, if a user previously installed the app via the traditional installer, that version would take priority in the system (e.g., in the PATH), which can lead to confusion or unexpected behavior when the portable version is installed via WinGet.

Proposed technical implementation details (optional)

Add a manifest option that allows a WinGet package to specify that any existing installation of the same application installed with a different installer technology should be uninstalled (or optionally prompted for removal) before or during the installation of the new package.

[DuckDuckStudio]

Is it helpful to use UpgradeBehavior: uninstallPreviousfor the portable installer?

[DanTheMan827]

I tried using UpgradeBehavior, but it refused because it was a different technology.

I suppose it's really more of a bug with the validation check, but #216705, #213818, and #229556 all had an issue with validation despite the manifest working fine in the Windows Sandbox.

I would have just started with the portable package, but it would've had an issue with the existing installed version.