Upgrade to Gradle 9

[StefanBratanov]

PR Description

https://docs.gradle.org/current/userguide/upgrading_major_version_9.html

Fixed Issue(s)

N/A

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

[zilm13]

so there are issues left like

Execution failed for task ':generateLicenseReport'.
> Resolution of the configuration ':acceptance-tests:runtimeClasspath' was attempted without an exclusive lock. This is unsafe and not allowed.

it's not a bug it's how Gradle was changed, see gradle/gradle#33938 (comment)

it could be resolved with disabling parallel, which is not a way we should go. So the issue (as I understand) is that subprojects have now stricter restrictions from access from root project and we try to access it too early. The first thing I'd try is move such projects in the end of execution queue by adding dependsOn. I've already tried general solutions like mustRunAfter allprojects.collectMany { it.tasks } or shouldRunAfter tasks.matching { it.name != 'generateLicenseReport' }. Probably need to add proper dependsOn.