Add 'org.hiero.gradle.check.gradle-properties' convention plugin

[jjohannes]

The gradle.properties file needs to be used to configure global switches directly in each repository. This can not be moved into these plugins, but the plugins may check if the build is configured as expected and otherwise emit a warning:

# Build Cache turned on?
org.gradle.configuration-cache=true

# Configuration Cache turned on?
org.gradle.caching=true

# JVM args contain '-Dfile.encoding=UTF-8'
org.gradle.jvmargs=-Dfile.encoding=UTF-8 ...

[jjohannes]

Also check that a minimal Gradle version of the plugins is met. If not, projects need to update Gradle together with the plugins.

Initially this will be Gradle 8.11.1.

[jjohannes]

Failing for the wrong minimal Gradle version will also allow us to indirectly use Dependabot to update Gradle regularly in the other repos. When we release a new version of these plugins for a new Gradle version, Dependabot will create a PR for updating org.hiero.gradle.build. Then the PR CI build will fail, telling to update Gradle as well as part of the PR.