Add optional UseSpecialSettings SFTP flow to CI

[masesdevelopers]

Description

Introduce a workflow input UseSpecialSettings to build.yaml, build_common.yaml and performance.yaml. When enabled (not intended for forks) the common workflow uses provided SFTP and special-settings secrets to: download pscp, fetch source.zip via SFTP, extract files with 7z using FIRST_SPECIAL_SETTINGS_PASSWORD/SPECIAL_SETTINGS_PASSWORD, list downloaded nupkg files and add a local NuGet source. Also propagate new secrets from build.yaml to the called common workflow. Steps are conditional and run on Windows (cmd) when the input is true.

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.