Issue #3420700 by Grimreaper: Enable Gitlab CI + Update README + Coding standards + Fix tests

.eslintrc

.gitlab-ci.yml

README.md

composer.json

drupalci.yml

entity_share.info.yml

modules/entity_share_async/entity_share_async.info.yml

modules/entity_share_async/entity_share_async.install

modules/entity_share_async/entity_share_async.module

modules/entity_share_client/entity_share_client.info.yml

modules/entity_share_client/entity_share_client.install

...s/entity_share_client/entity_share_client.post_update.php

modules/entity_share_client/entity_share_client.views.inc

.../entity_share_client/js/entity_share_client.full_pager.js

..._share_client/js/entity_share_client.import_processors.js

...src/ClientAuthorization/ClientAuthorizationPluginBase.php

...y_share_client/src/Commands/EntityShareClientCommands.php

modules/entity_share_client/src/Entity/ImportConfig.php

...ty_share_client/src/Event/RelationshipFieldValueEvent.php

modules/entity_share_client/src/Form/PullForm.php