@byContent should have a default functionality when no parameters are passed

Like the @byAttrVal annotation, when no parameters are passed, there is a default behaviour (in that case, matching the attribute with the same name of the property).

When I use @byContent without parameters, `@byContent()`, I expect a list of nodes, or a node (like a React.Fragment) wrapping everything inside the web component, maybe like the normal `this.props.children` property.

Start by locating the @byContent and @byAttrVal annotation implementations and their tests, then compare how each behaves when called without parameters. Clarify whether the result should be a node, a list, or a React.Fragment containing the web component's children, and consider the work complete when that behavior is specified, implemented, and covered by tests.

Written by the indexing model from the issue text.