add install-build-deps.sh and fix docker build procedure

docker/Dockerfile-ubuntu-22.04

@@ -1,13 +1,19 @@
 FROM ubuntu:22.04
 
 ARG DEBIAN_FRONTEND=noninteractive
-ARG workdir="/"
+ARG mscpdir="/mscp"
+
+COPY . ${mscpdir}
 
 RUN set -ex && apt-get update && apt-get install -y --no-install-recommends \
-	git cmake build-essential libssh-dev ca-certificates
+	ca-certificates
 
-RUN cd ${workdir}	\
-	&& git clone --depth=1 https://github.com/upa/mscp	\
-	&& mkdir mscp/build && cd mscp/build	\
-	&& cmake .. -DBUILD_PKG=1 \
+RUN ${mscpdir}/install-build-deps.sh
+
+RUN cd ${mscpdir}	\
+	&& rm -rf build
+
+RUN cd ${mscpdir}	\
+	&& cmake -B build -DBUILD_PKG=1	\
+	&& cd ${mscpdir}/build		\
 	&& cpack -G DEB CPackConfig.cmake