VNDK lib must not have `product_specific: true`

VNDK libs are system defined libraries. They must not be product
specific. Adding sanity check and a test to prevent setting
`product_specific: true` on VNDK libs.

Bug: 119575107
Test: building a vndk lib with 'product_specific: true,'
      must return error.

Change-Id: Ie0326540a692573f076ee08baf5d2e2f09d1007e