Implement Multi-Tag Scanning Support

[ho-229]

This PR introduces comprehensive support for scanning and managing multiple RFID tags simultaneously on a single RC522 scanner. The refactoring replaces the previous single-tag limitation with a configurable multi-slot system that can handle multiple tags concurrently.

BREAKING: Enhanced State Change Event Behavior

• Previous behavior: State change events were only triggered when tags were first detected (placed) or removed
• New behavior: State change events are now triggered on every scan cycle for all active tags
  • All detected tags are activated (RC522_PICC_STATE_ACTIVE or RC522_PICC_STATE_ACTIVE_H) and generate state change events during each polling cycle
  • RC522_PICC_STATE_READY and RC522_PICC_STATE_READY_H are not used currently cause we don't know which one was ready.
  • Applications can now perform operations on tags during any scan cycle, not just during initial detection

[ho-229]

Hi @abobija, PTAL