Investigate Dogtail's long-term viability

Part of the “Make test suite survive tech changes” roadmap item.

We have multiple concerns about the long-term viability of using Dogtail:

* intrigeri heard a GUADEC speaker mention that dogtail does not work on Wayland. If that’s indeed the case, then we should look into this problem before we keep porting tons of tests to dogtail: it would be a waste of time to do so only to have to port them to another technology again a year later. See https://gitlab.com/dogtail/dogtail/issues/3.

* The package is orphaned in Debian and was of course not updated to the latest upstream release.

* Fedora (and Redhat in general?) now uses openQA, which only supports image-based testing.

* Dogtail development has slowed down considerably since we adopted it. Here’s the a number of commits per year breakdown:

2011: 4
2012: 52
2013: 25
2014: 27
2015: 13
2016: 41
2017: 9

Parent Task: #12213

Related issues

• Related to #12191
• Blocks #12185 (closed)
• Blocks #15953

Original created by @intrigeri on 14585 (Redmine)