Get updated/opened project ID

## Every time, when already existing project saves or opened, or a new project creates, the planner sends the ID of this project to the client

Example of how to get projectId from Roomtodo planner:

<iframe
    frameborder="0"
    id="iframe"
    src="https://example.com/planner/matconfig">
</iframe>

<script>

window.addEventListener("message", messageListener);

function messageListener(e) {
    try {
        const dataObj = JSON.parse(e.data);
        if (dataObj.action === "set_project") {
            let projectId = data.projectId;
        }
    } catch (error) {
        console.error("Error parse JSON string!");
    }
}
</script>

Also JSON config for client's site has to contains 'enable_set_project': true:

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