move POM config to maven-publish convention plugin

[aSemy]

infrastructure Everything related to builds tools, CI configurations and project tooling

Continue migrating the build logic to use convention plugins #2703

It is a small part of simplifying the logic in build-logic/src/main/kotlin/org/jetbrains/publication.kt

Impact

This change has only one change: I removed the afterEvaluate {} logic for configuring the Dokka Gradle Plugin POM. The result is that the POM is now different.

(the PR is on the left, master is on the right)

I'd like to be able to avoid this, but I think that improving the build logic is better than trying to edit a POM that most people won't realise even exists!

Testing

I have tested this by

1. update dokka_version to be 1.8.20 (just so long as it's not a SNAPSHOT - otherwise the comparison below is impossible)
2. publishing to MavenProjectLocal
   ./gradlew publishAllPublicationsToMavenProjectLocalRepository
3. rename $rootDir/build/maven-project-local to $rootDir/build/maven-project-local-tmp
4. checking out master branch
5. re-run
   ./gradlew publishAllPublicationsToMavenProjectLocalRepository
6. comparing (with IntelliJ) $rootDir/build/maven-project-local with $rootDir/build/maven-project-local-tmp

[IgnatBeresnev]

Looking good, thank you! 👍

Pretty sure it's going to be OK, but I've triggered lengthy integration tests just in case, can be merged once they pass