Make the docker-related logic for doing a local packaged build on Linux match
with the Jenkins CI build for Linux.
Also fix the problems with packaged builds for Linux (local or CI) where
gstreamer errors were displayed in the terminal shortly after app start/login
and there was no sound output.
Changes:
- Adds `ci/Dockerfile` for creating `statusteam/nim-status-client-build:latest` used in builds
- Adds `ci/Jenkinsfile.linux` and `ci/Jenkinsfile.macos` for respective platforms
- Simplifies MacOS signing by adding `scripts/sign-macos-pkg.sh` script
- Makes `Makefile` use `scripts/sign-macos-pkg.sh` to make the DMG
- Makes `APPIMAGE` and `DMG` in `Makefile` modifiable by environment
- Adds `--passL:"-headerpad_max_install_names"` to `NIM_PARAMS` to fix MacOS signing issues
Signed-off-by: Jakub Sokołowski <jakub@status.im>