- update Kotlin from 1.7.10 to 2.0.21
- Kotlin 1.6 dependencies in Gradle lock files are expected because kotlinc,
which is also used by some tests, internally uses some 1.6 dependencies
for backwards compatibility reasons.
- update kotlinx-html and kotlinx-serialization
- adapt Kotlin code where necessary
- use Kotlin stdlib Path APIs where possible
- fix IntelliJ Kotlin inspection warnings
- reformat code with `./gradlew spotlessApply`
- ktfmt adds lots of trailing commas
- Add workaround to fix IntelliJ "unresolved reference" errors
This change activates the `TYPESAFE_PROJECT_ACCESSORS` feature
preview in Gradle, and switches to such accessors instead of
string-based project references, where possible
Relates-To: apple/pkl#204
Signed-off-by: Sam Gammon <sam@elide.ventures>
