Sign macOS binaries that aren't signed

[akoeplinger]

In dotnet/dotnet#308 we had to turn off signing a couple binaries again since it caused issues.
E.g. the mono-aot-cross would crash because it didn't expect the restrictions from Hardened Runtime.

We should fix that, but we don't necessarily need to fix the issues caused by Hardened Runtime right away since just signing is enough for the SDL requirements. That means setting CertificateName="MacDeveloper" for these files in Signing.props

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[ellahathaway]

Per dotnet/dotnet#824 (comment), please also investigate these files as well:

clang-19
llvm-*
node
python3*
wasm2js
wasm-*