Add testresult report

[omar-selo]

Resolves RTW-228.

Changes:

• Adds a new endpoint /v1/reports/testresults that returns a CSV file with information about test results (we can then use this csv file to find out interesting information like the tests that fail most)
• Make track, store, series and repo fields in artefact not nullable as it doesn't make sense to have two values that mean the same thing (problem was apparent in the report)
• Created a new DataGenerator class to help with generating dummy data for tests. Refactored existing create_artefact and create_user functions into it

Note:

• I didn't refactor all tests to use DataGenerator to create all of the objects yet, as that would make this PR too big. But can definitely do that in a future PR

Example CSV report file: testresults.csv

[andrejvelichkovski]

I think the reasoning for that is because we were intending to have this file easily importable in something like jupyter notebook where we can do different statistical analysis, and I think a common format in those is csv.

Not sure whether this is true, but another reason I can see is that csv might be slightly more compact representation of the data, as we don't need to duplicate the keys for each entry in the table, and we might save some space and time as I'm expecting this file becomes significantly large.

[omar-selo]

The main question I have, is "why csv and not json?"

Adding to @andrejvelichkovski's point, it's also much easier to play around with this data via some spreadsheet software. We can filter, sort, create charts, etc. With json we'd have to do these operations through code (unless there is a tool out there that makes this easier to work with through GUI).

[omar-selo]

Had to push some frontend changes as these backend changes caused the following issue: