feat(docker/node): dockerized node and appchain-pki network

[xendarboh]

• [x] Build and install all relevant binaries used by a node.
• [x] Use the resulting docker image for the local pki=appchain network.
  • [x] use Makefile to build the node docker image
  • [x] separate Makefile.appchain alongside default Makefile
  • [x] remove pki=appchain from Makefile
  • node startup mimics production deployment while supporting local dev
  • [x] use docker volume to pass network.yml to each container
  • [x] use docker volume for common data dir (configs, logs, etc)
  • [x] each node generates their own config for local test network, generate all node configs and single docker-compose.yml
  • [x] ?: create entry.sh script
• [x] docker-compose.yml: set docker user
• [x] docs(docker): update README
• [x] docs: add example .env file
• [x] feat(genconfig): save gateway-specific client files to unique directory: <identifier>-client(2)
  • (too intrusive for now, only applies to whole system config)
• [x] feat(genconfig): use absolute path for auth's (Gateways|Mixes|ServiceNodes).IdentityPublicKeyPem
• [x] feat(genconfig): add option -binary-prefix
  • like -binary-suffix
  • use it to set full path to installed ServiceNode plugin binaries
• [x] feat(genconfig): configure http_proxy ServiceNode plugin
• [x] feat: dynamic run-time http_proxy_config.toml
  • not part of Docker image
  • located in node's data-dir
  • genconfig can create an empty stub file, so the docker image is still functional by default