Excavator: Prepare for Gradle 9

[svc-excavator-bot]

excavator is a bot for automating changes across repositories.

Changes produced by the roomba/gradle-9-preparation check.

Migrate application.mainClassName to mainClass

Deprecated in Gradle 7.1, removed in Gradle 9.0.

The mainClassName property was removed in favour of the mainClass Property<String>. At the top level it must be qualified as application.mainClass — the replacement lives only on the extension, not as a project property — e.g.

apply plugin: 'application'

mainClassName = 'com.example.Main'

now becomes

apply plugin: 'application'

application.mainClass = 'com.example.Main'

Inside an application { } block it is set unqualified, e.g.

application {
    mainClassName = 'com.example.Main'
}

now becomes

application {
    mainClass = 'com.example.Main'
}

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