Support for Spresense SDK Additional Audio API's from CircuitPython

[TheMindVirus]

Further to some investigation into audioio and audiomixer being missing from the Spresense build of CircuitPython
and providing some basic support for setBeep() coming from Arduino, there are a whole lot more Audio DSP features
of the Spresense SDK and Carrier Board with built-in Headphone Jack that both this board and other boards could find
useful: #2676 (comment)

The Spresense has its own abstraction layer that may require a little bit of decluttering and integrating into an 8.x.x release
which would enable a subset if not all of the following features:

• Simple Tone with Frequency Playback (like Arduino Blink but Beep instead)
• MP3/WAV/Custom Encoded Audio File Playback with DSP Code Uploader
• Audio & Voice Recording and Effector Filter Design
• Additional Peripherals for other CircuitPython Boards (such as Secondary SD/Flash Memory, JPEG Camera and GNSS/LTE)

Block Diagram of CXD5602 ARM Peripherals: https://developer.sony.com/develop/spresense/docs/sdk_developer_guide_en.html
Audio Subsystem Specifics: https://developer.sony.com/develop/spresense/docs/sdk_developer_guide_en.html#_audio_subsystem

[tannewt]

@kamtom480 Do you have any suggestions on how this would be implemented? Have you looked into it?