datasette publish cloudrun (#434) - thanks, @rprimet

New publish subcommand that publishes using the
new Google Cloud Run platform.

    datasette publish cloudrun database.db

tests/test_utils.py

@@ -256,6 +256,29 @@ def test_temporary_docker_directory_uses_copy_if_hard_link_fails(mock_link):
             assert 1 == os.stat(hello).st_nlink
 
 
+def test_temporary_docker_directory_quotes_args():
+     with tempfile.TemporaryDirectory() as td:
+        os.chdir(td)
+        open('hello', 'w').write('world')
+        with utils.temporary_docker_directory(
+            files=['hello'],
+            name='t',
+            metadata=None,
+            extra_options='--$HOME',
+            branch=None,
+            template_dir=None,
+            plugins_dir=None,
+            static=[],
+            install=[],
+            spatialite=False,
+            version_note='$PWD',
+        ) as temp_docker:
+            df = os.path.join(temp_docker, 'Dockerfile')
+            df_contents = open(df).read()
+            assert "'$PWD'" in df_contents
+            assert "'--$HOME'" in df_contents
+
+
 def test_compound_keys_after_sql():
     assert '((a > :p0))' == utils.compound_keys_after_sql(['a'])
     assert '''