gck.env: Export all changed environment variables

Previously we would try to parse gck.env in a container. The better way is to export all Makefile exported variables that were changed during make execution already in a bash format.

This allows for easy inclusion and potentially conditional syntax in gck.env (not desired).

This also makes the gck.env to only be of make syntax instead of bash and make.

Overall this is much more predictable in a behavior, allowing us to control in a central place what variables and how they are exposed.

Next will be cleaning up the docker-compose.yml on what variables and where are exported.

Outcome

declare -x ADDITIONAL_DEPS="jq gdb autoconf"
declare -x BASE_IMAGE="registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.0.patched-golang-1.19-node-16.14-postgresql-12:rubygems-3.2-git-2.36-lfs-2.9-chrome-106-yarn-1.22-graphicsmagick-1.3.36"
declare -x BASE_IMAGE_REPOSITORY="registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.0.patched-golang-1.19-node-16.14-postgresql-12"
declare -x BASE_IMAGE_TAG="rubygems-3.2-git-2.36-lfs-2.9-chrome-106-yarn-1.22-graphicsmagick-1.3.36"
declare -x CUSTOM_GID="1000"
declare -x CUSTOM_MINIO_CONSOLE_PORT="9001"
declare -x CUSTOM_REGISTRY_PORT="5000"
declare -x CUSTOM_SSH_PORT="2299"
declare -x CUSTOM_UID="1000"
declare -x CUSTOM_WEBPACK_PORT="3808"
declare -x CUSTOM_WEB_PORT="3000"
declare -x DEBUG_CROSS_DB="1"
declare -x ENABLE_SPRING="1"
declare -x FORCE_WEBPACK_COMPILE="false"
declare -x GIT_EDITOR="nano"
declare -x GITLAB_MULTIPLE_DATABASE_METRICS="true"
declare -x RAILS_ENV="development"
declare -x USE_CABLE_SERVER="true"
declare -x USE_WEBPACK_DEV="false"
declare -x USE_WEB_SERVER="puma"

Extension of: !188 (merged).