[android] improve layout performance of Label

[jonathanpeppers]

Context: #12130
Context: https://github.com/angelru/CvSlowJittering
Context: https://github.com/jonathanpeppers/lols

Testing a customer sample and my LOLs per second sample, I could see a lot of time (5.1%) spent in PrepareForTextViewArrange():

1.01s (5.1%) microsoft.maui!Microsoft.Maui.ViewHandlerExtensions.PrepareForTextViewArrange(Microsoft.Maui.IViewHandler,Microsoft.Maui
635.99ms (3.2%) mono.android!Android.Views.View.get_Context()

Most of the time is spent just calling View.Context to be able to do:

internal static int MakeMeasureSpecExact(this Context context, double size)
{
    // Convert to a native size to create the spec for measuring
    var deviceSize = (int)context!.ToPixels(size);
    return MeasureSpecMode.Exactly.MakeMeasureSpec(deviceSize);
}

In eea91d3, I added an overload for ToPixels() that allows you to get the same value with an Android.Views.View -- avoiding the need to call View.Context.

So we can instead do:

internal static int MakeMeasureSpecExact(this PlatformView view, double size)
{
    // Convert to a native size to create the spec for measuring
    var deviceSize = (int)view.ToPixels(size);
    return MeasureSpecMode.Exactly.MakeMeasureSpec(deviceSize);
}

After these changes, it seems to be ~2.7% better:

420.68ms (2.4%) microsoft.maui!Microsoft.Maui.ViewHandlerExtensions.PrepareForTextViewArrange(Microsoft.Maui.IViewHandler,Microsoft.Maui

The View.Context call is now completely gone.

It appears to show a good result in the LOLs/second sample as well: