Generated files not accesible after upgrade to kotlin 2.0.0

Trying to migrate to Kotlin 2.0.0 and KSP 2.0.0-1.0.21, and was unsuccessful, as none of the generated files which are present in the build folder are visible to the source.

Reproducer:

Use 'examples/multiplatform' from this repository, change gradle.properties to use kotlin 2.0.0 and appropriate ksp:
```diff
diff --git a/examples/multiplatform/gradle.properties b/examples/multiplatform/gradle.properties
index 97b2b488..0049d2e1 100644
--- a/examples/multiplatform/gradle.properties
+++ b/examples/multiplatform/gradle.properties
@@ -1,3 +1,3 @@
org.gradle.jvmargs=-Xmx2048M
-kotlinVersion=1.9.21
-kspVersion=1.9.21-1.0.15
+kotlinVersion=2.0.0
+kspVersion=2.0.0-1.0.21
```
Observed:
```
./gradlew workload:compileKotlinJvm

> Task :workload:kspKotlinJvm
w: [ksp] [Bar.kt, Baz.kt]
w: [ksp] [Bar.kt, Baz.kt, Foo.kt]

> Task :workload:compileKotlinJvm FAILED
e: file:///home/ionspin/tmp/ksp/ksp/examples/multiplatform/workload/src/commonMain/kotlin/com/example/Bar.kt:4:15 Unresolved reference 'Foo'.
e: file:///home/ionspin/tmp/ksp/ksp/examples/multiplatform/workload/src/commonMain/kotlin/com/example/Baz.kt:4:15 Unresolved reference 'Foo'.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':workload:compileKotlinJvm'.
> A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
> Compilation error. See log for more details

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 695ms
5 actionable tasks: 2 executed, 3 up-to-date
```