[7.0] Declare as configuration cache compatible on the Gradle Plugin Portal

[PaintNinja]

The plugin portal now has a badge for plugins that declare they are configuration cache compatible and a table showing what they support:

With FG7 being designed to support configuration caching and play nice with Gradle's full suite of performance features, having this badge on the plugin portal would help raise awareness that it's now supported, especially for those upgrading from FG6.

https://plugins.gradle.org/docs/publish-plugin#declaring-compatibility

[Jonathing]

Sounds good.