Fix TypeNotPresentException in projects without KGP

[IgnatBeresnev]

Regression from 0a09318#diff-127cb17801c64a32309502eaee33392ad749494ba8022bef47e8002359ea1b8eL17

Before, it was loading a specific java class, so it failed with NoClassDefFoundError that was caught, and we returned null.

With Kotlin DSL, findByType() is trying to load reified T through Class#getGenericSuperclass, which throws TypeNotPresentException.

We don't expect that TypeNotPresentException will be thrown, so it's not caught and the user project is failing with

Caused by: java.lang.TypeNotPresentException: Type org.jetbrains.kotlin.gradle.dsl.KotlinProjectExtension not present
        at org.gradle.api.reflect.TypeOf.captureTypeArgument(TypeOf.java:301)
        at org.gradle.api.reflect.TypeOf.<init>(TypeOf.java:97)
        at org.jetbrains.dokka.gradle.UtilsKt$kotlinOrNull$$inlined$findByType$1.<init>(TypeOfExtensions.kt:28)
        at org.jetbrains.dokka.gradle.UtilsKt.getKotlinOrNull(utils.kt:43)

This can be reproduced on projects that don't have KGP applied.