Rename rebaseline-test to rebaseline-test-internal

Rename rebaseline-test to rebaseline-test-internal
https://bugs.webkit.org/show_bug.cgi?id=90485

Reviewed by Adam Barth.

It's now only used by other rebaseline commands. It's still useful to leave it
as it's own command to aid in debugging when something goes wrong. In a followup
patch, I'll make webkit-patch rebaseline cover any use-cases that rebaseline-test
might have covered.

We no longer need the --print-scm-changes option since the only caller always passes
that option in.

Also, make all the arguments command-line flags instead. Simplifies the code
a bit in my opinion.

* Scripts/webkitpy/tool/commands/rebaseline.py:
(RebaselineTest):
(RebaselineTest.__init__):
(RebaselineTest.execute):
(AbstractParallelRebaselineCommand._rebaseline_commands):
(RebaselineExpectations.execute):
* Scripts/webkitpy/tool/commands/rebaseline_unittest.py:
(test_rebaseline_all):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121799 268f45cc-cd09-0410-ab3c-d52691b4dbfc