Callers of LayoutEntityHelperTrait::getEntitySections() do not account for the view mode

Problem/Motivation

Once #2907413: Consider supporting Layout Builder Overrides for other view modes is addressed, sections will be stored per-view mode.

LayoutEntityHelperTrait::getEntitySections() assumes the view mode is default.

Proposed resolution

Provide additional functionality for displays, and do not assume the default display.

Remaining tasks

Per #3008924-27: Callers of LayoutEntityHelperTrait::getEntitySections() do not account for the view mode:

Thank you all! Sadly still needs tests and steps to reproduce to be committed. I don't have the time currently, sorry.

Steps to reproduce should follow, per #3008924-13: Callers of LayoutEntityHelperTrait::getEntitySections() do not account for the view mode:

Could you explain how to reproduce the bug, using only core modules?
Step by step, starting with "Install standard profile"
That is an important step for writing test coverage, which must be done before the fix can be committed.

User interface changes

N/A

API changes

TBD

Data model changes

N/A