Rename `testutil-logging` to `logging-testlib`

[alexander-yevsyukov]

Some other modules of the Spine SDK already have testlib submodules, e.g., ProtoData.

The testutil is the older convention we used to have. Let's fix the module name and its artifacts while we don't have external users.

The full artifact coordinates for JVM artifact should be io.spine:spine-logging-testlib-jvm:<version>.