feat(entity): remove addAll

[timdeschryver]

PR Checklist

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• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Closes #

What is the new behavior?

Does this PR introduce a breaking change?

[x] Yes
[ ] No

Other information

BREAKING CHANGE:

To overwrite the entities, we previously used the addAll method but the method name was confusing.

BEFORE:

adapter.addAll(action.entities, state);

AFTER:

The new method name setAll describes the intention better.

adapter.setAll(action.entities, state);