I2S: add opus stream and file support for opus/aac

[Staars]

Description:

Adds optional OPUS decoder, which is off by default. Adds 23076 bytes in test build.
Build flag: USE_I2S_OPUS

Internal decoder type is 2.

Adds file play support for all 3 decoders with similar syntax to web radio:
i2splay2 /clock.opus - plays raw OPUS file "clock.opus"
i2splay0 /clock.aac - plays raw AAC file "clock.aac" (M4A must be converted to AAC, countless online tools available).

Some refactoring with more generic naming and reduced code duplication.

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.3.1.1.250109
• I accept the CLA.

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

[s-hadinger]

Awseome. Thanks