fix(types): specified 'this' for getters and setters in fields

[knoid]

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Description of change

I'm bringing #11648 into v5.

Added typings for this on getters and setters in attribute definitions.

[sushantdhiman]

🎉 This PR is included in version 5.21.13 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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