message: bump dockerfiles to ubuntu 22.04 and add web-server container
diff: # Build stage #
  #################
  -FROM ubuntu:bionic AS build
  +FROM ubuntu:22.04 AS build
  # Install packaged dependencies
  RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
  @@ -53,11 +53,33 @@ COPY vendor vendor/
  RUN cargo build --release
  +######################
  +# Web server stage #
  +######################
  +
  +FROM ubuntu:22.04 AS web-server
  +
  +RUN apt-get update \
  + && DEBIAN_FRONTEND=noninteractive apt-get upgrade -y \
  + && DEBIAN_FRONTEND=noninteractive apt-get install -y \
  + ca-certificates \
  + tini \
  + && rm -rf /var/lib/apt/lists/*
  +
  +COPY --from=build /build/target/release/cratesfyi /usr/local/bin
  +COPY static /srv/docsrs/static
  +COPY templates /srv/docsrs/templates
  +COPY vendor /srv/docsrs/vendor
  +
  +WORKDIR /srv/docsrs
  +# Tini is a small init binary to properly handle signals
  +CMD ["/usr/bin/tini", "/usr/local/bin/cratesfyi", "start-web-server"]
  +
  ##################
  # Output stage #
  ##################
  -FROM ubuntu:bionic AS output
  +FROM ubuntu:22.04 AS output
  RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
  git \
  