Glow: [CI] Migrate to CircleCI and explore better parallelism

[rdzhabarov]

Travic CI runs are slow and there is a lot of contention on concurrent runs which slows down iteration on PRs from serval contributors.
See more details in https://github.com/pytorch/glow/issues/1763.

We would like to run even more tests which might take longer, see here.

This issue is to track progress on migrating Glow CI infrastructure to CircleCI.
See more details on CircleCI here.

[rdzhabarov]

see https://github.com/pytorch/glow/pull/1833 for some of the configuration added for CircleCI.

[rdzhabarov]

@zrphercule it looks like you are planning to tackle this. based on the latest quip I see ;)

[zrphercule]

@rdzhabarov Yeah =w= I just modified the build of onnx, since before that we cannot build using ninja. Hope we can tackle this next week.

[bertmaher]

Closing since we're on CircleCI now! Thanks @zrphercule!