ART: Arm32 packed-switch jump tables

Add jump table support to the thumb2 assembler. Jump tables are
a collection of labels for the case targets, and an anchor label
denoting the position of the jump.

Use the jump table support to implement packed-switch support for
arm32.

Add tests for BindTrackedLabel and JumpTable to the thumb2 assembler
test.

Bug: 24092914
Change-Id: I5c84f193dfebf9e07f48678efc8bd151bb1410dd