Context
MSBuild had been added to the code validation pipeline but was missing the tsa config file. Per the instructions here and after talking to Matt, adding this file
Changes Made
Added a tsa config file by copying from SDK
Testing
Not sure how to test this. I pushed an internal build but the checks didn't run as I'm told they run nightly in a separate pipeline.
Notes
Validation pipeline: https://dev.azure.com/dnceng/internal/_build/results?buildId=2157183&view=results