bigquery: test that model queries work
bigquery: test that model queries work

Test that CREATE MODEL and PREDICT both work, and also that we can
see a model when we list tables.

Change-Id: Ia4f9ef7e8a98043da953661bbc06d4f237dddd85
Reviewed-on: https://code-review.googlesource.com/30210
Reviewed-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Jean de Klerk <605b93664484fed1e671a07bff68da39e73d0174@google.com>

googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go