[CAL-1312] Booking metadata gets lost on reschedule

[zomars]

We want to store some metadata in the 'Booking' object. Here are some steps:
We append metadata query parameter to the booking link on our side before sending it to the user;
User opens the link and creates a meeting -> 'booking' is created with metadata object;
User clicks on the "Reschedule" button;
It redirects them to the initial page where they update date of the meeting;
After saving changes metadata disappears from the Booking object.
It happened because the user clicked on the "Reschedule" button they were redirected without including metadata to the link. I see two possible options:
Include metadata to the booking link when rescheduling the event;
Do patch for metadata when updating 'Booking', meaning to merge the previous metadata value with a new one.

_{From SyncLinear.com | CAL-1312}