Incompatibility with webprofiler

Problem/Motivation

When using this module and webprofiler, we can't add a new external entity type because ConfigurableExpressionFieldMapperBase use EntityTypeManager type instead of EntityTypeManagerInterface in constructor.

Steps to reproduce

1. Install external_entities module
2. Install webprofiler module
3. Add a new external entity type

Error :

Argument 4 passed to Drupal\external_entities\FieldMapper\ConfigurableExpressionFieldMapperBase::__construct() must be an instance of Drupal\Core\Entity\EntityTypeManager, instance of Drupal\webprofiler\Entity\EntityManagerWrapper given

Proposed resolution

Use EntityTypeManagerInterface in ConfigurableExpressionFieldMapperBase, ExpressionFieldMapperBase and FieldMapperBase classes constructors.

Remaining tasks

Using EntityTypeManagerInterface in ConfigurableExpressionFieldMapperBase, ExpressionFieldMapperBase and FieldMapperBase classes constructors.