Add `Level` method

#### Description:

Add method returning level of the element. It should cover all different storages like `LevelId` property, level parameters, level as host or base level for two level based elements.

The issue names no files, tests, or entry points. Start by locating the element types and existing LevelId, level-parameter, host-level, and base-level handling, then determine how one method can cover those storage patterns; done means the method returns the expected level for each stated element case.

Written by the indexing model from the issue text.