Berry math.inf, math.isinf() and fixed json ouput for inf and nan

[s-hadinger]

Description:

Berry anticipation of berry-lang/berry#421

Add support for math.inf representing the normalized Infinity:

• math.inf is infinity (positive), can be set as negative with -math.inf
• math.isinf() to test if a value is infinity

For json.dump, values inf, -inf and nan now convert to null which is the best match since inf and nan are not valid json values.

Related issue (if applicable): fixes #21296

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.3.0.0
• I accept the CLA.

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