Move CompilerDriver to dex2oat/.

Also DexToDexCompiler, QuickCompilerCallbacks and tests.

aosp_taimen-userdebug:
 - before:
   lib64/libart-compiler.so: 3112344
   lib/libart-compiler.so: 2312908
   bin/dex2oat: 563176
 - after:
   lib64/libart-compiler.so: 2986720 (-123KiB)
   lib/libart-compiler.so: 2219852 (-91KiB)
   bin/dex2oat: 635832 (+71KiB)

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing --jit
Change-Id: I36e63b83dff1d5c731d05de27d3663cfc81de6ad