Upgrade checkstyle and spotbugs tooling

[8Keep]

1. Upgrade spotbugs and checkstyle
2. Run them both as part of CI, but make them non blocking. Upload the logs so we can take a look whenever.
3. Move versioning into the unified version file just like everything else.

[8Keep]

New version of checkstyle requires jdk 21+.

[gemini-code-assist]

Code Review

This pull request updates the versions for Checkstyle and Spotbugs and adjusts their task configurations, including a transition from 'enabled' to 'required' for Spotbugs reports. It also introduces a Java version check to conditionally enable Checkstyle tasks. Feedback suggests that the Java 21 requirement is too restrictive and potentially incompatible with older Gradle versions, recommending a baseline of Java 17 instead. Furthermore, it is recommended to apply a similar version guard to Spotbugs tasks to prevent build failures on older JDKs.

[gemini-code-assist]

The Spotbugs tasks are not guarded by a Java version check, unlike the Checkstyle tasks in common.gradle. Since Spotbugs 4.8+ and its Gradle plugin 6.x require at least Java 17, running these tasks on older JDKs will cause the build to fail. Adding an enabled check ensures the tasks are skipped gracefully on unsupported environments, which aligns with the "non-blocking" goal stated in the PR description.

        tasks.withType(com.github.spotbugs.snom.SpotBugsTask) {
            enabled = JavaVersion.current().isCompatibleWith(JavaVersion.VERSION_17)
            reports {
                html.required = !project.hasProperty("xml-reports")
                xml.required = project.hasProperty("xml-reports")
            }
        }