Added files for arduino-cli and simpler arduino compiling

[FStefanni]

Hi,

this pr proposes the following improvements:

1. Now it is possible to install via Arduino/Arduino-cli thanks to the inclusion of library.properties file
2. Also, to allow this kind of installation, I added the src/PN532_LIB.h
3. I also fixed some wrong includes in the other files
4. Added a missing return statement
5. Fixed a wrong return statement (wrong: <, correct: <=)

It is possible to use everything as before, but if the library is installied via Arduino/Arduino-cli , the new usage is the following:

1. Include PN532_LIB.h wherever you need, choosing also the communication protocol, for example:

// Here we choose the I2C protocol:
//#define PN532_USE_HSU 1
#define PN532_USE_I2C 1
//#define PN532_USE_SPI 1
//#define PN532_USE_SWHSU 1
#include <PN532_LIB.h>

2. In just one .ino/.cpp file, include the implementation:

// We must always choose the same protocol, so let's continue with I2C in this example:
//#define PN532_USE_HSU 1
#define PN532_USE_I2C 1
//#define PN532_USE_SPI 1
//#define PN532_USE_SWHSU 1
// And here we include the implementation:
#define PN532_INCLUDE_IMPLEMENTATION 1
#include <PN532_LIB.h>

Regards

[Cincinnatu]

Hello. I will check soon whether this is effective and reasonable.