build: Enable the new Dokka Gradle plugin

[joc-a]

Description

• Why: This removes the warning that Dokka Gradle plugin V1 is deprecated.
• How: By following the guide here.

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Type of Change

Please mark the relevant options with an "X":

• Bug fix
• New feature
• Documentation update
• Other - Build

Updates/remove existing public API methods:

• Is breaking change

Affected databases:

• MariaDB
• Mysql5
• Mysql8
• Oracle
• Postgres
• SqlServer
• H2
• SQLite

Checklist

• Unit tests are in place
• The build is green (including the Detekt check)
• All public methods affected by my PR has up to date API docs
• Documentation for my change is up to date

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Related Issues

[bog-walk]

Some additional steps probably need to be taken:

1. Task dokkaHtmlMultiModule no longer exists in V2, so the github task for building api docs in docs-workflow.yml most likely needs to be changed as shown here.
2. Current set-up isn't showing warnings, but the guide does suggest switching to dokka { } DSL (see 'Output Directory' point in this section)
3. I'm not sure about this, but maybe changes suggested here need to also be made given that this is a multi-module project?

[joc-a]

Some additional steps probably need to be taken:

1. Task dokkaHtmlMultiModule no longer exists in V2, so the github task for building api docs in docs-workflow.yml most likely needs to be changed as shown here.
2. Current set-up isn't showing warnings, but the guide does suggest switching to dokka { } DSL (see 'Output Directory' point in this section)
3. I'm not sure about this, but maybe changes suggested here need to also be made given that this is a multi-module project?

@bog-walk I did steps 1 and 2. I wanted to do step 2 before but I was not sure because there was no clear replacement for DokkaMultiModuleTask in the documentation. As for step 3, I'm not sure either. It seems to be working without it locally, but we can try, and then open another PR later if it doesn't.

[bog-walk]

Sounds good to me 👍