ART: Instruction dumper should handle out-of-bound index for const-string

If const-string refers to out-of-bound index then we should handle it
similarly to PrettyField, PrettyMethod and PrettyType.

Change-Id: Ib6b1e20169e4b47c1cdb7dda80320ed21d61cfe3
Signed-off-by: Serdjuk, Nikolay Y <nikolay.y.serdjuk@intel.com>