compile for ESP32-IDF

[MDCservice]

Dear Bohdan and contributors,

I have ported the SimplePgSQL.h and .cpp to be used without the Arduino, but the ESP32-IDF framework instead. For now, its just hundreds of #ifdef ESP32_IDF ....., and it works for us.

There might be interests from other, to use these ESP32-IDF version as well, so I could contribute it, if there is interest. If so, I would also suggest to move out all the framework specific part in a own class or a own file, to separate the libqp-embedded part from the framework-specific code with all its #ifdefs. That would make porting and maintenance maybe easier.

Finally, I have developed a ResultSet class, based on C++ vectors, what internally handles columns and rows, orientated on the TDataset from Delphi/Free Pascal, what I could contribute.