Preventing warning in bootstrapper package self contained scenario #7009
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For 16.9 we made a change where bootstrapper packages can specify "0" for the public key value of a downloaded file and this will cause the bootstrapper to skip the public key comparison as long as the file is signed with a trusted MS cert. However, we didn't account for the scenario where a user wants to create a self contained bootstrapper, meaning it will include a copy of the package's installer. In this scenario we still perform the public key comparison and give a build warning when they don't match. This change skips this check when the package specifies 0 for the public key of the file in question.
Context
See the following thread: https://docs.microsoft.com/en-us/answers/questions/583383/publickey-token-warning-building-net-core-50-insta.html?childToView=602746#comment-602746
Changes Made
Skipping a check when a package's PublicKey value is set to "0".
Testing
Verified we no longer give this warning in this scenario, and that we still give it when the public key is non-zero and doesn't match the file on disk.