Add checks to validate the bouncer aliases values after API calls.

[MihaiTabara]

In bug 1470226 we're adding some suplimentary checks to make sure the updates we're performing against bouncer are correctly reflected on bouncer DB side. This one is specifically for the bouncer aliases job.

This PR takes care of it + some other things along the way:

• add/fix tests and keeps coverage at 100%
• rewrites the API calls from utils.py to be consitently prefix by api_... when are performed against bouncer API. The rest of them have more meaningful names
• add more logging
• add post-update-bouncer aliases checks to ensure values reflect reality
• the before checks were already added in https://github.com/mozilla-releng/bouncerscript/pull/16 a while ago

There is no API to call for bouncer aliases values, hence we're using the go-bouncer public interface to query for this data. Idea came here.

[coveralls]

Pull Request Test Coverage Report for Build 95

• 51 of 51 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 93:	0.0%
Covered Lines:	213
Relevant Lines:	213

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💛 - Coveralls

[MihaiTabara]

I triggered a bunch of tasks in staging releases and they work smoothly, modulo the fact that the product checks against downloads.mozilla.org are failing, as expected. This should work smoothly in production.

https://taskcluster-artifacts.net/M0wJJHI8TpSDS4Oz_gt54Q/0/public/logs/live_backing.log https://taskcluster-artifacts.net/eTXIxnDxTTO4XAzjbrgYoQ/0/public/logs/live_backing.log

[MihaiTabara]

This is looking good. Am merging this to master, it'll get picked up by the next roll-out of bouncerscript.