Added flatlands generator

[sh0inx]

• also added some logging about the generator type to ensure that server admins know what the correct enum values are

[PeachesMLG]

 /home/runner/work/IridiumSkyblock/IridiumSkyblock/src/main/java/com/iridium/iridiumskyblock/IridiumSkyblock.java:104: error: cannot find symbol
                getLogger().warning("Invalid generator type [" + IridiumSkyblock.getInstance().getConfiguration().generatorType + "], valid types are " + Arrays.toString(GeneratorType.values()));

Looks like you are missing an import or something?

[sh0inx]

tbh i might be lol, let me fix it rq