Implementing Gatsby v5 Slices API

[naomatheus]

Implementing Gatsby v5 Slices API

Related to issue: #524

The implementation of the Slices API requires some design planning, state management work, and react context management. This makes it necessary to split it into a new issue focused specifically on the Slices API implementation.

A brief discussion on the implementation details can be found in this Draft PR: #562.

Recommended resources:

📖 Please review the previous discussion here: #562.
⚠️ Note: styled-components is NOT compatible with Gatsby v5 Slices API, and there are no plans to support it. A recommended alternative is the @emotion/styled dependency. It has a syntax that closely resembles styled-components, allowing for a simple switch in the import from styled-components to @emotion/styled.
🧪 Lastly, ensure to test the project's production build for compatibility within the CI environment.