Added method EnableAllAttributeArrays()

This method is for convenience and to balance out the existing method
DisableAllAttributeArrays().

In addition, return 0 from GetNumberOfAttributeArrays() if attribute
(POINT, CELL, etc.) is not available instead of signaling an error.

Change-Id: I321e3028ef380c203b0ebc7d715e1b18987cca0d
Merge topic 'generalize_python_view' into next

ada8c849 Added method EnableAllAttributeArrays()