Nginx reverse proxy combined with Starman server in one image (#46)

* feat: provide image with nginx

* Re-use parent container configuration and startup scripts

* Rewrite proxy Dockerfile:

* ARCH used to be hard-coded; is now set according to the architecture being built
* Build from the associated LedgerSMB base image (not from 'lsmb-split')
* More deletion of non-required files (/usr/share/doc/*)
* Fewer layers by combining RUN commands

* Use 'server-start' script generated by the installer instead of repeating ourselves

* Don't expose the status module

It won't be accessible anyway: the localhost address is the one inside the container...

* Ensure relative redirects

When the container port :80 is exposed as :8080 on the host,
nginx redirects to http://localhost:80/login.pl with a relative
path, instead of http://localhost:8080/login.pl; the container
isn't bound to :80, so that request fails...

* Rename proxy layer image

* Adjust 'build' script to publish base and regular images

---------

Co-authored-by: Walid Mujahid <walidmujahid@gmail.com>

build

@@ -6,9 +6,19 @@ ${DOCKER:-docker} buildx build \
    --progress plain \
    --platform ${PLATFORM:-linux/amd64,linux/arm64,linux/arm/v7} \
    --build-arg "ARTIFACT_PATH=$ARTIFACT_PATH" \
+   -t ledgersmb/ledgersmb:$BRANCH-base \
+   -t ledgersmb/ledgersmb:$VERSION-base \
+   -t ghcr.io/ledgersmb/ledgersmb:$BRANCH-base \
+   -t ghcr.io/ledgersmb/ledgersmb:$VERSION-base \
+   ${SET_LATEST_TAG:+ -t ledgersmb/ledgersmb:latest-base -t ghcr.io/ledgersmb/ledgersmb:latest-base} \
+   --push base/
+
+${DOCKER:-docker} buildx build \
+   --progress plain \
+   --platform ${PLATFORM:-linux/amd64,linux/arm64,linux/arm/v7} \
    -t ledgersmb/ledgersmb:$BRANCH \
    -t ledgersmb/ledgersmb:$VERSION \
    -t ghcr.io/ledgersmb/ledgersmb:$BRANCH \
    -t ghcr.io/ledgersmb/ledgersmb:$VERSION \
    ${SET_LATEST_TAG:+ -t ledgersmb/ledgersmb:latest -t ghcr.io/ledgersmb/ledgersmb:latest} \
-   --push .
+   --push proxy/