Refactored duels-api and duels-plugin

[sukarangolani]

I have refactored the following classes as part of my course assignment:

• Duels/duels-plugin/src/main/java/me/realized/duels/extension/ExtensionClassLoader
• Duels/duels-plugin/src/main/java/me/realized/duels/spectate/ SpectateManagerImpl
• Duels/duels-plugin/src/main/java/me/realized/duels/setting/Settings
• Duels/duels-plugin/src/main/java/me/realized/duels/gui/settings/SettingsGui
• Duels/duels-api/src/main/java/me/realized/duels/api/event/match/MatchEvent
• Duels/duels-api/src/main/java/me/realized/duels/api/event/match/MatchStartEvent
• Duels/duels-api/src/main/java/me/realized/duels/api/event/match/MatchEndEvent
• Duels/duels-plugin/src/main/java/me/realized/duels/duel/DuelManager

The following refactoring techniques have been performed:

• Extract method
• Rename variable
• Move method
• Pull up method
• Extract class

[RemainingToast]

Otherwise it looks like a good refactor

[Realizedd]

Thanks for the request! I don't think I can merge this due to recent changes I've made, but I'll take them into account for the next update.