Add dequickening support.

Both vdex and BCI require full dequickening support. This
change implements dequickening by using the existing encoded
quickening, and adds the checkcast quickening to that encoding.

bug: 30937355
bug: 32369913
Test: dex_to_dex_decompiler_test.cc test-art-host

Change-Id: Ie95f46946d59b28157d6e47dcf4a859be032d1c3