1.1.0 Economy and Nexo Block+furniture support

feat: Add Nexo integration and economy-based respawn costs

• Integrated Nexo API for handling custom furniture and block events:
  • Added NexoFurnitureListener to handle Nexo furniture placement and breaking.
  • Added NexoBlockListener to handle Nexo note block placement and breaking.
• Implemented economy-based respawn costs:
  • Updated RespawnEconomy to include chargeForRespawn method.
  • Made respawn costs configurable via config.yml.
• Updated PwingGraves to register Nexo listeners conditionally based on plugin availability.
• Enhanced configuration:
  • Added settings for Nexo furniture and block IDs in config.yml.
  • Updated messages.yml to include economy-related messages.
• Fixed malformed code in RespawnEconomy.java.
• Updated plugin.yml to declare Nexo as a soft dependency.
• Cleaned up and refactored listeners for better modularity and maintainability.

Example Usage:

1. Nexo Furniture:

   • Place a Nexo furniture item with the configured ID (e.g., nexo:beacon) to create a respawn point.
   • Break the furniture to remove the associated respawn point.

2. Nexo Block:

   • Place a Nexo note block with the configured ID (e.g., nexo:beacon) to create a respawn point.
   • Break the block to remove the associated respawn point.