Add check for Genome optional dependency

[vedant-shroff]

Fixes the following error that was logged during the week long playtest server running MetalRenegades which includes SimpleFarming

10:32:08.121 [main] ERROR o.t.engine.ComponentSystemManager - Failed to load system SimpleFarming:GenomeAuthoritySystem
java.lang.NoClassDefFoundError: org/terasology/genome/breed/mutator/GeneMutator
        at java.base/java.lang.Class.getDeclaredConstructors0(Native Method)
        at java.base/java.lang.Class.privateGetDeclaredConstructors(Class.java:3137)
        at java.base/java.lang.Class.getConstructor0(Class.java:3342)
        at java.base/java.lang.Class.newInstance(Class.java:556)
        at org.terasology.engine.ComponentSystemManager.loadSystems(ComponentSystemManager.java:99)
        at org.terasology.engine.modes.loadProcesses.RegisterSystems.step(RegisterSystems.java:54)
        at org.terasology.engine.modes.StateLoading.update(StateLoading.java:237)
        at org.terasology.engine.TerasologyEngine.tick(TerasologyEngine.java:472)
        at org.terasology.engine.TerasologyEngine.mainLoop(TerasologyEngine.java:435)
        at org.terasology.engine.TerasologyEngine.run(TerasologyEngine.java:411)
        at org.terasology.engine.Terasology.main(Terasology.java:155)

The optional dependency of Genome is checked before loading the system, rather than relying on an error to cause the system to fail to load.

How to test :

• Create a game with SimpleFarming activated but without Genome
• This game should not log an error when trying to load the GenomeAuthoritySystem, but should ignore this system altogether
• Create a game with both SimpleFarming and Genome enabled
• The GenomeAuthoritySystem should load successfully, this can be verified by running the HeldGenomeCheck after harvesting a bush and holding the seed in your hand.