Add an installBehavior.disableLicenseDisclaimer setting to hide the install license disclaimer #6598

Relevant area(s)

WinGet CLI

Description of the new feature / enhancement

Every package install prints two lines before it starts:

This application is licensed to you by its owner.
Microsoft is not responsible for, nor does it grant any licenses to, third-party packages.

There is no way to turn this off. --silent only affects the installer's own UI, and --ignore-warnings
does nothing for it because the disclaimer is written at info level. For upgrade --all or import
over many packages, and in scripts, the repeated disclaimer buries the output people need.

Related: #288 (the disclaimer is misleading for Microsoft's own packages), #3891 (--silent still prints
it), #6419 (same request for the winget configure disclaimer).

Questions for maintainers

1. Is a setting acceptable for this, given that the default stays unchanged?
2. Is the name disableLicenseDisclaimer fine (it mirrors disableInstallNotes)?

Proposed technical implementation details

One boolean setting, modeled on the existing installBehavior.disableInstallNotes:

"installBehavior": {
    "disableLicenseDisclaimer": true
}

• Default is false, so nothing changes unless a user opts in.
• It is a setting only. I am deliberately not proposing a command-line argument, to keep this small;
  one could follow later if wanted.
• Because Settings::User() is global, it applies everywhere the disclaimer is printed, including
  upgrade --all, import and dependency installs, with no per-command wiring.
• Only the two license lines are affected. The Microsoft Store message ("This package is provided through
  Microsoft Store...") is a different notice and stays.