Added Compatibility to ESP32 and ESP8266

[rseidt]

On the ESP platform the SerialConfig enum is defined as an int32 instead of int16 as for the other platforms. So based on the idea of PR #16 from @mostafahk which seems kind of abondoned (last commit 2 years ago) I made the type dynamic.
Based on this change this will enable the ModBus Library to work on the espressifs

[github-actions]

Memory usage change @ 9692cbc

Board	flash	%	RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A
arduino:samd:mkr1000	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrfox1200	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrgsm1400	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrnb1500	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrvidor4000	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwan1300	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwan1310	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrwifi1010	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrzero	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

Click for full report table

Board	examples/RS485Passthrough flash	%	examples/RS485Passthrough RAM for global variables	%	examples/RS485Receiver flash	%	examples/RS485Receiver RAM for global variables	%	examples/RS485Sender flash	%	examples/RS485Sender RAM for global variables	%
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
arduino:samd:mkr1000	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrfox1200	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrgsm1400	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrnb1500	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrvidor4000	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwan1300	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwan1310	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrwifi1010	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrzero	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

Click for full report CSV

Board,examples/RS485Passthrough<br>flash,%,examples/RS485Passthrough<br>RAM for global variables,%,examples/RS485Receiver<br>flash,%,examples/RS485Receiver<br>RAM for global variables,%,examples/RS485Sender<br>flash,%,examples/RS485Sender<br>RAM for global variables,%
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
arduino:samd:mkr1000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrfox1200,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrgsm1400,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrnb1500,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrvidor4000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwan1300,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwan1310,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrwifi1010,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrzero,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