Update docker build script to ignore local-only build artifact

Node modules "installed" are left on the host via mounted directories.
This would cause an annoyance where to build new docker, clean docker
images, this directory would have to be removed every time. This change
adds this fixed, known directory to the dockerignore file, so it will
never be considered for addition to a docker image build, and the build
script was updated to appropriately ignore this file in the clean check.

.dockerignore

@@ -5,3 +5,4 @@
 /model_files
 /unity
 /ros_bags
+/ros/angel_utils/multi_task_demo_ui/node_modules

angel-docker-build.sh

@@ -54,29 +54,36 @@ done
 #       part of docker builds. Maybe read this in from somewhere else instead
 #       of encoding here?
 warn_build_spaces=(
-  "${SCRIPT_DIR}/ros"
-  "${SCRIPT_DIR}/docker"
-  "${SCRIPT_DIR}/pyproject.toml"
-  "${SCRIPT_DIR}/poetry.lock"
-  "${SCRIPT_DIR}/angel_system"
-  "${SCRIPT_DIR}/tmux"
+  "ros"
+  "docker"
+  "pyproject.toml"
+  "poetry.lock"
+  "angel_system"
+  "tmux"
 )
 # Check if there are tracked file modifications.
-git_status="$(git status --porcelain "${warn_build_spaces[@]}")"
-git_sm_status="$(git submodule foreach git status --porcelain)"
-git_sm_q_status="$(git submodule --quiet foreach git status --porcelain)"
+git_status="$(cd "${SCRIPT_DIR}" && git status --porcelain "${warn_build_spaces[@]}")"
+git_sm_status="$(cd "${SCRIPT_DIR}" && git submodule foreach git status --porcelain)"
+git_sm_q_status="$(cd "${SCRIPT_DIR}" && git submodule --quiet foreach git status --porcelain)"
 # Check if there are ignored files in the workspace that should not be there.
-git_clean_dr_cmd=( git clean "${warn_build_spaces[@]}" -Xdn )
-git_clean_dr="$("${git_clean_dr_cmd[@]}")"
+# Items that are excluded here (-e) are paths that are included in *both* the
+# .gitignore and .dockerignore files.
+git_clean_dr_cmd=(
+  git clean
+  "${warn_build_spaces[@]}"
+  -e "ros/angel_utils/multi_task_demo_ui/node_modules/"
+  -xdn
+)
+git_clean_dr="$(cd "${SCRIPT_DIR}" && "${git_clean_dr_cmd[@]}")"
 # Check for unclean files in submodules not caught by the above.
 # Quiet version is for checking, non-quiet version is for reporting (it's
 # informational).
 git_sm_clean_dr_cmd=( git submodule foreach --recursive git clean -xdn )
 git_sm_q_clean_dr_cmd=( git submodule --quiet foreach --recursive git clean -xdn )
 # shellcheck disable=SC2068
-git_sm_clean_dr="$(${git_sm_clean_dr_cmd[@]})"
+git_sm_clean_dr="$(cd "${SCRIPT_DIR}" && ${git_sm_clean_dr_cmd[@]})"
 # shellcheck disable=SC2068
-git_sm_q_clean_dr="$(${git_sm_q_clean_dr_cmd[@]})"
+git_sm_q_clean_dr="$(cd "${SCRIPT_DIR}" && ${git_sm_q_clean_dr_cmd[@]})"
 if [[ -n "${git_status}" ]] || [[ -n "${git_sm_q_status}" ]] || [[ -n "${git_clean_dr}" ]] || [[ -n "${git_sm_q_clean_dr}" ]]
 then
   log "WARNING: Docker/ROS workspace subtree is modified and/or un-clean."