Enhancement: Update PlaceMarker component to allow custom zoom/buffer

[ajolipa]

Currently there is no way to pass a user-specified default zoom level to the PlaceMarker component, which would be useful for some use cases (e.g. Ground Beneath our Feet embedded maps in posts). This could be accomplished via a buffer prop perhaps, and/or through a default zoom level which is then passed to the map.flyTo or map.jumpTo method when the map is loaded or the place URL updated. (Relevant documentation for the latter here: https://docs.maptiler.com/sdk-js/api/map/)