drive: Make CopyOperation aware of locally created files

Perform copy locally if the file is dirty or it doesn't have a resource ID.
Fix Copy()'s behavior to overwrite existing file.
Remove dependency from MoveOperationTest to CopyOperation.

BUG=260539,331985
TEST=unit_tests
R=kinaba@chromium.org

Review URL: https://codereview.chromium.org/149413002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247834 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247834