feature: add flag for beacon effects of other plots (#3627)

* feature: add flag for beacon effects of other plots

Took 7 minutes

* fix: don't add the beacon effect flag if the platform is not paper

Took 2 minutes

* fix: creating consistency in documentation

Took 7 minutes

* feature: add global paper setting for the beacon-effect

* fix: description of the plot flag and rewrite of the listener

* fix: renamed flag and added road support

* fix: renamed flag and changed flag functionality

* fix: added spigot fallback listener and fixed NPE

* refactor: Address checkstyle violations

* addition: remove beacon effects when player leaves a plot

* fix: updated javadoc and fixed usage of the PlotListener#addEffect method

* chore: Run license updater

Co-authored-by: BuildTools <unconfigured@null.spigotmc.org>
Co-authored-by: Alexander Brandes <mc.cache@web.de>

Core/src/main/resources/lang/messages_en.json

@@ -618,6 +618,7 @@
   "flags.flag_description_prevent_creative_copy": "<gray>Prevents people from copying item NBT data in the plot unless they're added as members.</gray>",
   "flags.flag_description_leaf_decay": "<gray>Set to `false` to prevent leaves from decaying.",
   "flags.flag_description_projectiles": "<gray>Prevents guests from shooting projectiles on the plot when set to false.</gray>",
+  "flags.flag_description_beacon_effect": "<gray>Enables beacon effects on the plot.</gray>",
   "flags.flag_error_boolean": "Flag value must be a boolean (true | false).",
   "flags.flag_error_enum": "Must be one of: <list>",
   "flags.flag_error_integer": "Flag value must be a whole positive number.",