Rewrite deprecated references and update some docs based on inspection

composer.json

...s/salesforce_example/salesforce_example-apex_endpoint.php

modules/salesforce_mapping/src/Event/SalesforcePullEvent.php

...es/salesforce_mapping/src/Event/SalesforcePushOpEvent.php

...salesforce_mapping/src/Form/SalesforceMappingFormBase.php

...es/salesforce_mapping/tests/src/Unit/MappedObjectTest.php

modules/salesforce_pull/src/DeleteHandler.php

modules/salesforce_pull/src/Plugin/QueueWorker/PullBase.php

modules/salesforce_pull/tests/src/Unit/DeleteHandlerTest.php

modules/salesforce_pull/tests/src/Unit/PullBaseTest.php

modules/salesforce_pull/tests/src/Unit/PullQueueItemTest.php

modules/salesforce_pull/tests/src/Unit/QueueHandlerTest.php

modules/salesforce_push/salesforce_push.install

...rce_push/src/Plugin/SalesforcePushQueueProcessor/Rest.php

modules/salesforce_push/src/PushQueue.php

modules/salesforce_push/tests/src/Unit/PushQueueTest.php

...h/tests/src/Unit/SalesforcePushQueueProcessorRestTest.php

tests/src/Unit/RestClientTest.php