Explicit setup for Mockito inline mocking

[mrotteveel]

We need to add explicit configuration for Mockito inline mocking. Currently, it produces the following warnings (on Java 21+):

Mockito is currently self-attaching to enable the inline-mock-maker. This will no longer work in future releases of the JDK. Please add Mockito as an agent to your build as described in Mockito's documentation: https://javadoc.io/doc/org.mockito/mockito-core/latest/org.mockito/org/mockito/Mockito.html#0.3
WARNING: A Java agent has been loaded dynamically (C:\Users\mark\.gradle\caches\modules-2\files-2.1\net.bytebuddy\byte-buddy-agent\1.17.7\fbf3d6d649ed37fc9e9c59480a05be0a26e3c2da\byte-buddy-agent-1.17.7.jar)
WARNING: If a serviceability tool is in use, please run with -XX:+EnableDynamicAgentLoading to hide this warning
WARNING: If a serviceability tool is not in use, please run with -Djdk.instrument.traceUsage for more information
WARNING: Dynamic loading of agents will be disallowed by default in a future release

See also https://javadoc.io/doc/org.mockito/mockito-core/latest/org.mockito/org/mockito/Mockito.html#0.3

We'll need to check if this also works on older Java versions (i.e. Java 8, 11, and 17 for Jaybird 5, and only Java 17 for Jaybird 6 and 7), or if we need version-dependent config.