Update oms.coffee to work with AdvancedMarkerElement

Changes:

Google didn't provide an equivalent for getVisible in AdvancedMarkerElement; I'm not quite sure how this was intended to be used - whether it was asking "is this marker's location within the bounds of the map" or "is this marker status visible vs. invisible". So I created a new method IsVisibleMarker that returns true if the marker has a non-null map (map == null is how you remove a marker from the map) AND is within the bounds of that maps latitude/longitude boundaries. This works for my purposes, I hope it is the correct definition
changed getPosition/setPosition to .position property
changed getZIndex/setZIndex to .zIndex property
commented out the line "(return i if o is obj) for o, i in arr" in p.arrIndexOf. If I'm understanding Coffee correctly (I'm not!!) this never gets called if arr.indexOf is defined, so this seems to work...

Probably worth noting a few other things I had to do to migrate to AdvancedMarkerElement:

No longer use defered script include, so I no longer get a callback when it is loaded, so the old code of waiting for both oms and maps to load no longer works. E.g., now I load googlemaps with (g => { var h, a, k, p = "The Google Maps JavaScript API", c = "google", l = "importLibrary", q = "ib", m = document, b = window; b = b[c] || (b[c] = {}); var d = b.maps || (b.maps = {}), r = new Set, e = new URLSearchParams, u = () => h || (h = new Promise(async (f, n) => { await (a = m.createElement("script")); e.set("libraries", [...r] + ""); for (k in g) e.set(k.replace(/[A-Z]/g, t => "_" + t[0].toLowerCase()), g[k]); e.set("callback", c + ".maps." + q); a.src = https://maps.${c}apis.com/maps/api/js? + e; d[q] = f; a.onerror = () => h = n(Error(p + " could not load.")); a.nonce = m.querySelector("script[nonce]")?.nonce || ""; m.head.append(a) })); d[l] ? console.warn(p + " only loads once. Ignoring:", g) : d[l] = (f, ...n) => r.add(f) && u().then(() => d[l](f, ...n)) })({ key: "...", v: "weekly", // Use the 'v' parameter to indicate the version to use (weekly, beta, alpha, etc.). // Add other bootstrap parameters as needed, using camel case. });

So now I need to create the overlappingmarkerspiderfier in oogle.maps.event.addListenerOnce(this.gmap, 'idle', function () { ...}

jawj / OverlappingMarkerSpiderfier