Allow for optional custom installer switches

Description of the new feature / enhancement

In the manifest schema, there is a field for custom installer switches, which are always applied. However, packages may support other custom switches that users may want to use without having to use the override parameter. If there was an ability to add these as optional switches and to show them in winget show, it could make for a better overall experience

Proposed technical implementation details

Thought 1 - Change InstallerSwitches > Custom to an array type of CustomSwitch objects

InstallerSwitches:
    Silent: "/quiet"
    Custom:
    - Switch: NoRestart
      Value: "/suppressReboot"
      Default: true
    - Switch: NoDesktopIcon
      Value: "/desktopicon=0"
      Default: false

User would run winget install example.package --silent --NoDesktopIcon and the package would be installed using example.package.exe /quiet /suppressReboot /desktopicon=0

Thought 2 - entirely new manifest field

InstallerSwitches:
    Optional:
        NoDesktopIcon: "/desktopicon=0"
        UseAppdataFolder: "/appdata=1"

User could run winget install example.package --UseAppdataFolder

Edit: Thought 3 - Allow for them to be under Installer Switches

InstallerSwitches:
    Silent: “/quiet”
    Custom: “/norestart”
    NoDesktopIcon: "/desktopicon=0"
    UseAppdataFolder: "/appdata=1"

Start by locating the manifest schema handling and the code paths for winget install and winget show, since no specific files or tests are named. Compare the three proposed representations and trace how custom switches are parsed, displayed, and passed to installers. Done means an agreed optional-switch design is supported in manifests, shown by winget show, and accepted by installation commands.