Refactor dexopt command args

Move a bunch of char* to std::string.

Will fix fork potential fork problems in a followup.

Test: adb shell data/nativetest/installd_dexopt_test/installd_dexopt_test
Bug: 116059983

Change-Id: I8fdf96cfe0343042d1a868ca09e6c6b9a629b967