[Inputstream] Make API backwards compatible to old addons

[peak3d]

Description

Currently Matrix inputstream addons doesn't build because of the API change introduced here: #16581

Motivation and Context

Allow nightly builds

How Has This Been Tested?

Compiled win32

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)