Design improvement for how components are identified in SPA SDK

Currently, the SPA SDKs recognize components based on a label property that is not sufficiently stable or unique. This is used to determine which e.g. React component should be used to render a specific component described by the Page Model API. We think that we can do better by introducing new behavior in the SDK based on the component catalog ID rather than the label. We need to discuss the details, come up with a final proposal, and make a plan for how this should be implemented in both the backend and the SDKs.