[Enhancement]: apply Gradle best practices

Module

Core

Proposal

Apply Gradle build practices so the build configuration does not take ~10 sec for every execution.

Currently, the project configuration takes ~11 seconds on Apple M1 which is very noticeable.
For instance, if I add a dependency to one of the modules, I have to wait for 10 seconds for the IDE to refresh. It does not have to be that long.

The slowness might be related to creating a lot of tasks eagerly "thanks" to old Groovy DSL code.

For instance, the code like the following always creates japicmp, and check tasks even in the case they will not be executed. The tasks are not required for IDE to pick up the updated project dependencies.

tasks.japicmp {
    dependsOn(tasks.shadowJar)
}
...

    project.tasks.check.dependsOn(japicmp)

PS. It would be nice to move to Kotlin DSL as per General Gradle Best Practices as well.

Start with the Core module's Gradle configuration and measure the reported roughly 11-second configuration time on an Apple M1. Inspect the eager task declarations shown in the issue and compare configuration behavior before and after the changes. Done means unnecessary tasks are not created during IDE dependency refresh and configuration time is reduced.