Issue 16430 - String>> asSymbol no protected against concurrent access (alternative solution)

[carolahp]

Proposes solution to issue https://github.com/pharo-project/pharo/issues/16430

Summary

To prevent data races when new symbols are interned into the NewSymbols table, a semaphore is used to protect the critical code section in the method Symbol >> intern

[carolahp]

I see the image was built , but (I think) unrelated tests are failing