[all] Replace find by contains

[alxbilger]

Before C++20, checking if a collection contains a value was done by using find and comparing to a sentinel (e.g. m_broadPhaseCollisionModels.find(firstCollisionModel) != m_broadPhaseCollisionModels.end()).

This approach is error-prone:

• You must not forget to compare find to a iterator
• The iterator can be unrelated to the searched collection

In C++20, .contains can be used instead, eliminating the mentioned risks of error. In addition, the intention is clearer.

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Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).

[alxbilger]

[ci-build][with-all-tests]