NethVoice: Implement SFTP Access for Recordings

[Amygos]

This feature request aims to provide a secure and convenient way
to access and manage recordings. Implementing SFTP access will allow users to
transfer recordings securely, reducing the risk of data breaches and
unauthorized access.

Proposed solution

The proposed solution involves adding a container that mounts the moh (message
of the day) as a volume and serves it via SFTP. To achieve this, the following
steps will be taken:

• Request the additional from NS8 for SFTP access.
• Utilize the NethVoice admin password for SFTP access, ensuring that only authorized
  personnel can access the recordings.
• Implement a persistent /etc/ssh configuration to avoid changing the host key
  and allow the addition of public keys to authorized_keys, enabling secure
  and convenient access.

Alternative solutions

Alternative approaches considered include:

• Using alternative file transfer protocols, such as FTP or HTTP, however,
  these protocols do not provide the same level of security as SFTP.
• Implementing a custom solution for recording access, but this would likely
  require significant development and maintenance efforts.