Fatal error if taxonomy is not installed

Problem/Motivation

If Taxonomy module is not installed on a site, when navigating to the Block Configure screen, a fatal error is thrown:

Drupal\Component\Plugin\Exception\PluginNotFoundException: The "taxonomy_vocabulary" entity type does not exist.

Steps to reproduce

Proposed resolution

I would suggest either:

1. Move the not_taxonomy_vocabulary condition into its own sub-module, similar to the block_visibility_conditions_commerce sub-module.
2. And/or, in NotConditionPluginBase ensure that the entity type exists before trying to load it.

Technically speaking the same error will also be raised if Node is not installed.

Remaining tasks

User interface changes

API changes

Data model changes