Use content_translation.manager service to check entity is translatable

Problem/Motivation

In automatic translation feature to create a translation request when the entity is inserted/updated we need to check if it is translatable.

Steps to reproduce

Enable and configure automatic translation from AT-LS settings for a non translatable entity.

Proposed resolution

Inject content_translation.manager service to check it.

Remaining tasks

Use content_translation.manager service to check entity is translatable

User interface changes

None

API changes

None

Data model changes

None