Update embedded Groovy and Groovy DSL Language to 4.0

[pioterj]

The current plan is to upgrade to Groovy 4 in the next major release (8.0).

However an alternative path could be to stick with Groovy 3.x a bit longer. This is however tied to the evolution of Java Language version support planned for Groovy 3.
In short, Gradle would require Groovy 3 to still be compatible with Java 21 (September 2023 release)

[pioterj]

Preparation being done in:

• Prepare for Groovy 4 upgrade gradle#18665
• Conditionally enable Groovy 4 for testing gradle#20038

[ljacomet]

The update of Gradle using Groovy 4 has been pushed out of Gradle 8.0 and will only be done for Gradle 9.0