Berry Serial config to change parity on-the-fly for RS-485

[s-hadinger]

Description:

Experimental feature to change Serial parity on-the-fly as required for RS-485 9 bit communication.

You can call serial.config(serial.SERIAL_8E1) and serial.config(serial.SERIAL_8O1) to invert parity. You can also change stop bits and number of significant bits.

Related issue (if applicable): fixes #22272

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.3.1.0.240926
• I accept the CLA.

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