Clustering: ClusterContent's and ItemContent's `contentDescription` is not taken into account for talkback accessibility .

#### Environment details
Android API 35
Library Version: 6.1.1

#### Steps to reproduce
1. Create a GoogleMap composable with a Clustering composable inside of it.
2. The Clustering's ItemContent and ClusterContent params are setup with custom composables which have their `contentDescription` set to different texts(i.e. for cluster: "Cluster of x items" and for markers "Marker with y title").
3. Activate Talkback on the Android OS.
4. Run the app
5. Try to select a cluster or a marker
6. Actual result: Talkback says "Map Marker" instead of the expected "Cluster of x items"/"Marker with y title"

#### Code example
This is an example how we have setup the renderer for the Clustering:
```
val renderer = rememberClusterRenderer(
clusterContent = { cluster ->
ClusterContent(
numberOfItems = totalItemCount,
isSelected = isSelected
)
},
clusterItemContent = { mapItemGroup ->
if (isStacked()) {
StackedMarkerContent(
items = items,
)
} else {
CustomItemMarkerContent(
item = items.first()
)
}
},
clusterManager = clusterManager
)
```
Please note that i've noticed that in the top left corner of the map there are some invisible marker/cluster views which are selectable by talkback and those have the content description correctly read by talkback.

Inizia dal composable Clustering e dal relativo renderer dei cluster, quindi riproduci il problema con TalkBack usando descrizioni dei contenuti personalizzate per ItemContent e ClusterContent. Traccia come queste descrizioni vengono propagate ai marker della mappa selezionabili; il lavoro è completato quando TalkBack legge il testo personalizzato del marker o del cluster invece di "Map Marker".

Scritto dal modello di indicizzazione a partire dal testo della issue.