fix: add google.maps.Animation mock

[Green00101]

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Fixes #332 🦕

This PR adds the missing google.maps.Animation mock with BOUNCE and DROP constants.

After calling initialize(), users can now access:

google.maps.Animation.BOUNCE
google.maps.Animation.DROP

This fixes the issue where code using google.maps.Animation.BOUNCE could fail in tests because google.maps.Animation was not defined.

This PR also adds tests to verify that google.maps.Animation is initialized with BOUNCE and DROP.

Tests passed:

• npm test
• npm run lint

I am happy to update the code if any changes are needed.

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