Add compact-dex-level argument to dex2oat

No-op right now but will be passed to dexlayout to generate
CompactDex.

Added the following dex2oat options:
--compact-dex-level=none generates no CompactDex.
--compact-dex-level=fast generates CompactDex with optimizations
that are fast and take low resources.

Will add test in follow up through dex2oat/compact_dex_file_test.

Test: test-art-host-gtest
Bug: 63756964

Change-Id: If9d6f4a383bdad1086b3e37daefe108bdd5cd36d