Add: useScript hook

[fabiankaegy]

Description of the Change

The useScript hook allows you to load dynamic script tags on the page from within your react application. This is useful for things like form / video embeds where the script url may include a specific identifier.

Usage

function BlockEdit( props ) {
    const { attributes } = props;
    const { formId } = attributes;

    const { hasLoaded, scriptElement } = useScript( `https://example.com/${formId}` );

    return (
        ...
    );
}

Closes #21

Alternate Designs

Possible Drawbacks

Verification Process

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Changelog Entry

Added useScript tag to easily load dynamic script URLs on the page

Credits

Props @Shelob9