cr: Print a list of closest matching targets when no match is found

When the user passes in an invalid target name, print a list of closest
matches as a hint:

    $ cr build chromium_test_shell
    Invalid target chromium_test_shell as chromium_test_shell
    Did you mean chromium_testshell, libchromiumtestshell or chromium_testshell_paks?

NOTRY=true

Review URL: https://codereview.chromium.org/136553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244507 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244507