Berry add file.savecode()

[s-hadinger]

Description:

Add file.savecode() function to save pre-compiled Berry bytecode (.bec files) from native Berry code. This allows to generate .bec files in CI.

From upstream berry-lang/berry#441

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.2.7.7
• The code change is tested and works with Tasmota core ESP32 V.3.0.2
• I accept the CLA.

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