Import selectors apply API methods allow to unsafely reference symbols via Strings

## Compiler version

main

## Expectation
Import selectors apply API methods allow to reference symbols via their names, which is unsafe and incongruent to the rest of the API (where we reference things via Symbols. We should not pass Strings directly to those apply methods, instead we should rely on Symbols

See: https://github.com/scala/scala3/pull/22457