Berry added close() to class serial

[s-hadinger]

Description:

Added explicit close() method to Berry serial class.

Internally it's just a synonym to deinit() but you are not supposed to call deinit() yourself, it is only called by the garbage collector.

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.2.7.6
• The code change is tested and works with Tasmota core ESP32 V.2.0.14
• I accept the CLA.

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