This change updates OpenSSL from 1.1.1w to 3.5.2. The code works as-is, but many functions have been marked as deprecated and thus will need to be rewritten. For now we explicitly add the `-DOPENSSL_SUPPRESS_DEPRECATED` to give us time to do so, while providing us with the benefits of the updated version.
* Copy Antithesis SDK version 0.4.0 to directory external/
* Add build option `voidstar` to enable instrumentation with Antithesis SDK
* Define instrumentation macros ASSERT and UNREACHABLE in terms of regular C assert
* Replace asserts with named ASSERT or UNREACHABLE
* Add UNREACHABLE to LogicError
* Document instrumentation macros in CONTRIBUTING.md
