Refactor custom events name dispatched by mapml-viewer

[AliyanH]

refactor custom events dispatched by mapml-viewer so they don't clash with leaflet events, ex. "zoomend" -> "map-zoomend".
All events - https://maps4html.org/web-map-doc/docs/api/mapml-viewer-api#events
https://github.com/Maps4HTML/Web-Map-Custom-Element/blob/94fa0896a87504777bb58c808e0b5f805926b2cf/src/mapml-viewer.js#L619-L852

[prushforth]

See also