Extract dedicated containers

[99linesofcode]

• [x] Do away with separate PHP containers for development and PHP versions;
• [x] Remove EXPOSE and VOLUME from containers, should be configurable by the end user, imo;
• [x] Combine all commands into a single RUN so clean up actually reduces the overall image size;
• [x] Extend images from those that live inside ghcr.io/99linesofcode;
• [x] Build Neovim from source in devcontainer;