Upgrade Dokka/Dokkatoo to version 1.9, when fixed

[jbartok]

Initially, we upgraded to Dokka 1.9/Dokkatoo 2.0.0 in this PR.
Then we found out there is a flaky bug in Dokka, the fix for it seems to have just missed the 1.9 release.
We have reverted the upgrade and have asked Jetbrains for a patch release.
Even if they make one, Dokkatoo will need an upgrade too, before we can try bumping the version again.

[aSemy]

Even if they make one, Dokkatoo will need an upgrade too,

Hopefully Dokkatoo won't need a separate release and you can just bump the Dokka version that Dokkatoo uses

https://github.com/adamko-dev/dokkatoo/blob/v2.0.0/modules/dokkatoo-plugin/src/main/kotlin/DokkatooExtension.kt#L122

In fact you might even be able to try using a dev release of Dokka, assuming you add the JetBrains dev repo: https://slack-chats.kotlinlang.org/t/15731482/running-into-an-interesting-error-on-our-ci-with-dokka-comin#8e89e8c8-a88c-4766-bd52-cb8a4f3e4d85