New Feature: Add API to draw a “direction cone” (sector shape) easily

Nobody has claimed this yet.

### Description

Currently, the Mapbox Maps SDK for Android does not provide a built-in way to render a *direction cone* (also known as a sector, view cone, or field-of-view arc).
Developers must manually compute latitude/longitude points along an arc and create a polygon to visualize a directional area — for example, a **Qibla direction cone** or **camera field of view**.

This requires repetitive math and custom logic:

* Computing arc coordinates using spherical trigonometry
* Handling wrap-around at 0°/360° and anti-meridian crossings
* Creating polygons manually with `PolygonAnnotation` or `FillLayer`

#### Example use case

Visualizing directional areas such as:

* Camera or compass “view cones”
* Radar or sensor field of view
* Qibla direction cone from a user’s location

#### Suggested solution

Add a lightweight helper API to easily draw a directional cone centered on a `Point`, given:

* `center`: geographic point (latitude, longitude)
* `bearing`: direction in degrees
* `halfAngle`: cone spread in degrees
* `radius`: distance in meters or kilometers
* `fillColor` / `fillOpacity`: optional styling

##### Example usage

```kotlin
mapView.annotations.createDirectionCone(
center = Point.fromLngLat(lon, lat),
bearing = heading,
halfAngle = 25.0,
radius = 300000.0, // meters
fillColor = Color.parseColor("#6600EEFF"),
fillOpacity = 0.35
)
```

Expected behavior:

* SDK internally computes and renders the cone polygon
* Automatically handles projection and anti-meridian issues
* Provides consistent results across zoom levels and map projections

---

## Why

Drawing a simple fan-shaped area currently requires non-trivial math and boilerplate, which developers have to reimplement in every project.
A built-in API would:

* Simplify rendering of directional indicators
* Reduce code duplication across apps
* Improve maintainability and readability
* Enable new UX patterns (e.g., navigation view cones, AR guidance, Qibla direction indicators)

Start with the mapView.annotations entry point and review the existing PolygonAnnotation and FillLayer approaches mentioned in the issue. Clarify the API design and verify that the resulting cone supports the listed center, bearing, halfAngle, radius, styling, projection, and anti-meridian requirements.

Written by the indexing model from the issue text.