Add poll() return status

[hmueller01]

Implement a return state to poll() to do something like

    if (!mqtt_client.poll()) {
      attemptReconnect();
    }

[github-actions]

Memory usage change @ 5eeec19

Board	flash	%	RAM for global variables	%
arduino:esp32:nano_nora	🔺 +16 - +20	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:mbed_giga:giga	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:mbed_nicla:nicla_vision	🔺 0 - +64	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:mbed_opta:opta	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A
arduino:megaavr:uno2018	🔺 +24 - +26	+0.05 - +0.05	0 - 0	0.0 - 0.0
arduino:renesas_portenta:portenta_c33	🔺 0 - +8	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:renesas_uno:unor4wifi	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkr1000	🔺 +16 - +16	+0.01 - +0.01	0 - 0	0.0 - 0.0
arduino:samd:mkrwifi1010	🔺 +16 - +16	+0.01 - +0.01	0 - 0	0.0 - 0.0
arduino:samd:nano_33_iot	🔺 +16 - +16	+0.01 - +0.01	0 - 0	0.0 - 0.0
esp32:esp32:esp32	🔺 +16 - +16	0.0 - 0.0	0 - 0	0.0 - 0.0
esp8266:esp8266:huzzah	N/A	N/A	N/A	N/A

Click for full report table

Board	examples/WiFiAdvancedCallback flash	%	examples/WiFiAdvancedCallback RAM for global variables	%	examples/WiFiEcho flash	%	examples/WiFiEcho RAM for global variables	%	examples/WiFiEchoCallback flash	%	examples/WiFiEchoCallback RAM for global variables	%	examples/WiFiSimpleReceive flash	%	examples/WiFiSimpleReceive RAM for global variables	%	examples/WiFiSimpleReceiveCallback flash	%	examples/WiFiSimpleReceiveCallback RAM for global variables	%	examples/WiFiSimpleSender flash	%	examples/WiFiSimpleSender RAM for global variables	%
arduino:esp32:nano_nora	16	0.0	0	0.0	16	0.0	0	0.0	16	0.0	0	0.0	20	0.0	0	0.0	20	0.0	0	0.0	20	0.0	0	0.0
arduino:mbed_giga:giga	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:mbed_nicla:nicla_vision	64	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:mbed_opta:opta	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
arduino:megaavr:uno2018	24	0.05	0	0.0	26	0.05	0	0.0	26	0.05	0	0.0	26	0.05	0	0.0	26	0.05	0	0.0	26	0.05	0	0.0
arduino:renesas_portenta:portenta_c33	0	0.0	0	0.0	0	0.0	0	0.0	8	0.0	0	0.0	8	0.0	0	0.0	0	0.0	0	0.0	8	0.0	0	0.0
arduino:renesas_uno:unor4wifi	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkr1000	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0
arduino:samd:mkrwifi1010	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0
arduino:samd:nano_33_iot	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0	16	0.01	0	0.0
esp32:esp32:esp32	16	0.0	0	0.0	16	0.0	0	0.0	16	0.0	0	0.0	16	0.0	0	0.0	16	0.0	0	0.0	16	0.0	0	0.0
esp8266:esp8266:huzzah	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A

Click for full report CSV

Board,examples/WiFiAdvancedCallback<br>flash,%,examples/WiFiAdvancedCallback<br>RAM for global variables,%,examples/WiFiEcho<br>flash,%,examples/WiFiEcho<br>RAM for global variables,%,examples/WiFiEchoCallback<br>flash,%,examples/WiFiEchoCallback<br>RAM for global variables,%,examples/WiFiSimpleReceive<br>flash,%,examples/WiFiSimpleReceive<br>RAM for global variables,%,examples/WiFiSimpleReceiveCallback<br>flash,%,examples/WiFiSimpleReceiveCallback<br>RAM for global variables,%,examples/WiFiSimpleSender<br>flash,%,examples/WiFiSimpleSender<br>RAM for global variables,%
arduino:esp32:nano_nora,16,0.0,0,0.0,16,0.0,0,0.0,16,0.0,0,0.0,20,0.0,0,0.0,20,0.0,0,0.0,20,0.0,0,0.0
arduino:mbed_giga:giga,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:mbed_nicla:nicla_vision,64,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:mbed_opta:opta,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:mbed_portenta:envie_m7,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A
arduino:megaavr:uno2018,24,0.05,0,0.0,26,0.05,0,0.0,26,0.05,0,0.0,26,0.05,0,0.0,26,0.05,0,0.0,26,0.05,0,0.0
arduino:renesas_portenta:portenta_c33,0,0.0,0,0.0,0,0.0,0,0.0,8,0.0,0,0.0,8,0.0,0,0.0,0,0.0,0,0.0,8,0.0,0,0.0
arduino:renesas_uno:unor4wifi,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkr1000,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0
arduino:samd:mkrwifi1010,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0
arduino:samd:nano_33_iot,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0,16,0.01,0,0.0
esp32:esp32:esp32,16,0.0,0,0.0,16,0.0,0,0.0,16,0.0,0,0.0,16,0.0,0,0.0,16,0.0,0,0.0,16,0.0,0,0.0
esp8266:esp8266:huzzah,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A