Dingtian: add inverted outputs and support shared PL/RCK pin

[baetzst]

Description:

Add support for the esp32_relay_x8_modbus (303E32DC812) board by
allowing inverted relay outputs and shared PL/RCK control pins in the
ESP32 Dingtian driver.

GPIO Mapping

GPIO	74HC595	74HC165	Tasmota
33	SIN	–	Dingtian SDI
25	RCK	!PL	Dingtian PL
26	SCK	CP	Dingtian CLK
27	–	Q7	Dingtian Q7
13	!OE	!CE	Dingtian OE

This fixes incorrect relay behavior caused by the board-specific GPIO
mapping.

Related issue (if applicable): n/a

Checklist:

• The pull request is done against the latest development branch
• Only relevant files were touched
• Only one feature/fix was added per PR and the code change compiles without warnings
• The code change is tested and works with Tasmota core ESP8266 V.2.7.8
• The code change is tested and works with Tasmota core ESP32 V.3.1.9
• I accept the CLA.

NOTE: The code change must pass CI tests. Your PR cannot be merged unless tests pass

[s-hadinger]

I don't like these kinds of compile time options that make overall firmware management a nightmare. This should be rather a parameter or a template option. I know nothing about MODBUS so I can't help

[baetzst]

This is not about Modbus. It is about adapting an already existing driver, xdrv_90_esp32_dingtian_relay.ino, to support the board mentioned above.

[Jason2866]

Still, the fact beeing ModBus or not. Make the feature non compile dependent would be more nice.