[Enhancement] LinearAccelerationSensor on Android

## Summary
The current Xamarin.Essentials Accelerometer provides generic access to an accelerometer sensor across the platforms. It would be good to allow a way to change the requested sensor to be the LinearAccelerationSensor on Android only. The LinearAccelerationSensor excludes gravity from the readings which is very handy.

https://developer.android.com/guide/topics/sensors/sensors_motion#sensors-motion-linear
https://github.com/dotnet/maui/blob/main/src/Essentials/src/Accelerometer/Accelerometer.android.cs

## API Changes
Add an optional method parameter for the type of sensor you want to request. It falls back to Accelerometer on any platforms where other platforms are not supported.

``` charp
public static void Start(SensorSpeed sensorSpeed, AccelerometerType? accelerometerType);
```

``` csharp
public enum AccelerometerType
{
Accelerometer = 0,
AccelerometerUncalibrated = 1, // why not? :)
LinearAcceleration = 2,
Gravity = 3, // why not? :)
}
```

``` csharp
Accelerometer.Start(SensorSpeed.UI, AccelerometerType.LinearAcceleration);
```

## Intended Use Case
Linear acceleration data is very useful. There are lots of times when you want to exclude gravity from any measurements.