feat: use pyarrow stream compression, if available

[plamut]

Closes #579.

This PR uses pyarrow compression of BQ Storage streams when available, i.e. when a recent enough version of google-cloud-bigquery-storage is installed.

Currently blocked on the BQ Storage release that will add this support, but it's still possible to test this PR locally by changing the noxfile to use a development version of google-cloud-bigquery-storage.

PR checklist

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[plamut]

Do we actually need pyarrow version check?

The bqstorage extra already pins the minimum pyarrow version to 1.0.0, thus I suppose if somebody somehow installs a less recent version, it can be considered an error on the user side?

[tswast]

Sounds good to me (removing this check). Since all of our extras require > 1.0.0, I'm okay with failing.

Counterpoint though is: what error will they get when pyarrow is too low? I wonder if we should file an FR to check for minimum versions and throw nicer errors? It might help with some of the issues like #556. This would mean keeping minimum versions in sync with 3 locations: setup.py, constraints.txt, and version_check.py, though.

[plamut]

The new pip dependency resolver (announcement) is significantly stricter, thus I suppose this will become a no-issue once its use is widespread enough and/or becomes a default. It shouldn't even be possible to install an incompatible pyarrow version with it.

Yes, we can open a FR to discuss there if covering this presumably corner-case scenario in the transitional period is worth doing, considering the problem with keeping the min versions in sync.

[tswast]

Currently blocked on the BQ Storage release that will add this support

Oops! I'll see what open PRs we have and hopefully cut a release today.

[plamut]

I see that a new version of BQ Storage has been released, good. But I now also see that one of the Python 3.6 unit tests fails, will investigate.

Update:
When Python 3.6 is used, the google-cloud-bigquery-storage version 2.0.0 is installed, and not the latest 2.4.0, hence the AttributeError in the test itself. It's because we have a non-empty constraints file for Python 3.6 test dependencies.