Add copier gain feature

[iganakov]

This PR introduces the Copier Gain feature which will be used by DMIC and with Microphone Privacy.

Gain algorithm utilizes Xtensa HiFi3 instruction set for efficient audio processing and has following modes:

• Static gain
• Transition gain (fade-in/fade-out)
• Mute

Gain has an option to change gain coefficients in runtime using DMA Control IPC message, therefore has dependency on
#9156: [DNM] basefw: Add handling of IPC4_DMA_CONTROL messages

Common use cases:

• control level of the audio signal coming from DMIC interface
• initial DMIC DC offset removal
• mute/unmute in case of Microphone Privacy
• simplification of detector pipelines (no need for volume and selector components)