[Tools] Create EntityRevisionAdd tool

Tool details:

• Label: Entity Revision Add
• Description: Adds a new unsaved revision to an existing entity.
• Class name: EntityRevisionAdd
• Plugin id:entity_revision_add
• Module:tool:tool_content

Tool inputs:

• Entity (entity)(entity)(required)

Tool outputs:

• Updated Entity (updated_entity)(entity)(required)

doExecute()

Create a new unsaved revision of the specified entity.

checkAccess()

TBD.