Remove VSM8 shadow type, add 16bit PCF shadow types for engine v2

[mvaligursky]

In engine v2, we have new shadow types:
playcanvas/engine#7142

We have also removed VSM8 support:
playcanvas/engine#7146

and shadow type constants were renamed:
playcanvas/engine#7145

we might want to migrate data - if the user had VSM8 selected, we might need to change it to VSM16.

we need to reflect these changes in the inspector of the Light, and also in the settings of the Clustered Rendering,
when editor is running in v2 mode.