Make it easier to deploy removal of modules which have associated entities

[alberto56]

Modules such as shortcut install starter data, so they're hard to remove.

To reproduce:

• ./scripts/deploy.sh
• ./scripts/ssh.sh
• drush pmu shortcut (this gives an error)
• drush entity:delete shortcut
• drush pmu shortcut (now this works)
• exit
• ./scripts/export-config.sh
• ./scripts/destroy.sh
• ./scripts/deploy.sh

This will fail with the very ugly error:

[error]  Drupal\Core\Config\ConfigImporterException: There were errors validating the config synchronization.
Entities exist of type <em class="placeholder">Shortcut link</em> and <em class="placeholder">Shortcut set</em> <em class="placeholder">Default</em>. These entities need to be deleted before importing. in Drupal\Core\Config\ConfigImporter->validate() (line 748 of /var/www/html/core/lib/Drupal/Core/Config/ConfigImporter.php). 

In ConfigImportCommands.php line 357:
                                                                              
 The import failed due to the following reasons:                              
 Entities exist of type <em class="placeholder">Shortcut link</em> and <em c  
 lass="placeholder">Shortcut set</em> <em class="placeholder">Default</em>.   
 These entities need to be deleted before importing.                          
                                                                              

config:import [--preview [PREVIEW]] [--source SOURCE] [--partial] [--diff] [-h|--help] [-q|--quiet] [-v|vv|vvv|--verbose] [-V|--version] [--ansi] [--no-ansi] [-n|--no-interaction] [-d|--debug] [-y|--yes] [--no] [--remote-host REMOTE-HOST] [--remote-user REMOTE-USER] [-r|--root ROOT] [-l|--uri URI] [--simulate] [--pipe] [-D|--define DEFINE] [--notify [NOTIFY]] [--druplicon] [--xh-link XH-LINK] [--] <command> [<label>]

This actually is sensible: it's refusing to delete data (in this case shortcuts in the starter database).

There are a few workarounds:

• option 1: go to the uninstall page of the GUI and follow the link to remove the offending entities
• option 2: remove the entities with drush: drush entity:delete shortcut
• option 3: drush ev '\Drupal::EntityTypeManager()->getStorage("shortcut_set")->load("default")->delete();'
• option 4: update the starter database once you removed the offending entities. (./scripts/update-starter-data.sh)

In some cases (as with "shortcut") you don't really care about the entities, so you could delete them in ./drupal/scripts/update.sh, however running "drush entity:delete shortcut" is not idempotent: it will fail if there are no such entities.

In this ticket, it would be nice to document a way to document how to uninstall modules whose entities we do not care about, and make deployment seamless.