Reaction API

- [ ] [React to a message](https://nextcloud-talk.readthedocs.io/en/latest/reaction/#react-to-a-message)
- [ ] [Delete a reaction](https://nextcloud-talk.readthedocs.io/en/latest/reaction/#delete-a-reaction)
- [ ] [Retrieve reactions of a message by type](https://nextcloud-talk.readthedocs.io/en/latest/reaction/#retrieve-reactions-of-a-message-by-type)

The issue links to the Nextcloud Talk Reaction API documentation. Start by reading the linked docs to understand the three required endpoints: reacting to a message, deleting a reaction, and retrieving reactions by type. Look at the existing API client structure in the repository to see how other endpoints are implemented. Implement the corresponding methods in the client, ensuring they match the API spec. Test the new methods against a Nextcloud Talk instance or with mock responses.

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