Code refactor with share/im-config_setting

Code refactor (stop wayland support)

* No call to 70im-config_launch from im-launch
* No call to 70im-config_launch from im-config_wayland.sh
* Use systemd_cat/logger for error messages
* Use IM_CONFIG_ENTRY
* Updated README.internal and README.Debian
* DEBUG logging IM_CONFIG_DEBUG
* Drop menus for non-existing programs
* dgit-maint-native workflow
* salsa CI with more autopkgtest
* Wayland support code sections are disabled with 'false'
  See https://bugs.debian.org/1052005 for the background

Closes: #1052005