Add carbon to a couple python imports for correctness (#1033)

executable_semantics/syntax/format_grammar_test.py

@@ -8,7 +8,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 import unittest
 
-from executable_semantics.syntax import format_grammar
+from carbon.executable_semantics.syntax import format_grammar
 
 
 class TestFormatGrammar(unittest.TestCase):

proposals/scripts/new_proposal_test.py

@@ -11,7 +11,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 import os
 import unittest
 
-from proposals.scripts import new_proposal
+from carbon.proposals.scripts import new_proposal
 
 
 class TestNewProposal(unittest.TestCase):