testserver: Move the target dir to /tmp/

When mounting in the repository, along with its target directory, we
might have some issue if the host arch does not match the guest
arch. We'd either use the host binary on the guest arch, or we end up
compiling the guest into the host target dir, meaning the host won't
work anymore.

By moving the target dir into a separate directory we then don't touch
the hosts' binaries.

docker/gl-testserver/Dockerfile

@@ -15,7 +15,8 @@ ENV PATH=$PATH:/home/$DOCKER_USER/.local/bin/:/opt/bitcoin/bin:/home/$DOCKER_USE
 ENV REPO=$REPO_PATH
 
 # Force this target dir, so the scripts can find all the binaries.
-ENV CARGO_TARGET_DIR=$REPO/target
+#ENV CARGO_TARGET_DIR=${REPO}/target
+ENV CARGO_TARGET_DIR=/tmp/target/
 
 RUN apt update && apt install -qqy \
     curl \
@@ -57,6 +58,9 @@ RUN cd /tmp/ && \
 RUN mkdir -p ${REPO_PATH} && \
     chown $DOCKER_USER:users ${REPO_PATH}
 
+ADD ../../libs/ ${REPO_PATH}/libs
+ADD ../../pyproject.toml ${REPO_PATH}/
+
 ADD ../../ ${REPO_PATH}/
 RUN chown $DOCKER_USER:users -R ${REPO_PATH}
 RUN chown $DOCKER_USER:users -R /home/$DOCKER_USER
@@ -69,10 +73,13 @@ RUN curl \
     -s -- -y --default-toolchain ${RUST_VERSION}
 RUN rustup default stable
 
-RUN curl -LsSf https://astral.sh/uv/install.sh | sh
-
 WORKDIR ${REPO_PATH}/libs/gl-testserver/
 
+RUN cargo build --bin gl-plugin
+RUN cargo build --bin gl-signerproxy
+
+RUN curl -LsSf https://astral.sh/uv/install.sh | sh
+
 RUN uv sync --locked -v
 RUN uv run clnvm get-all
 CMD uv run gltestserver run --metadata ${REPO}/ --directory ${REPO}/.gltestserver