Fix docker-compose and Dockerfile

[darkcl]

This PR fixes some issue when ACE-step is running through docker compose, changes the following:

• bump version for cuda to 12.8 to resolve dependency issue
• install ffmpeg
• add torchcodec
• remove appuser to resolve the write permission issue (any reason why we need appuser in the first place 🤔 ?)
• remove the dependency on remote git repo to local file in both Dockerfile and docker-compose

Related Issue: #237