Add a flag for determining whether to use a local Kythe.
Add a flag for determining whether to use a local Kythe.

Test Plan: bazel test //shipshape/cli:shipshape_test_prod

Reviewers: ciera

Reviewed By: ciera

Differential Revision: https://phabricator-dot-shipshapecode.appspot.com/D114

google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape,google/shipshape