Performance testing (OSOE-360)

[Piedone]

Performance testing (both server and client-side) at least on the level of "this is much slower than usual".

• We could also use Chrome performance logging. (This was previously broken in Selenium but is supposed to work with the v4 WebDriver we're using; this would also allow creating HAR files.) However, Selenium advises against using it for performance testing and we'd need a more complex setup with the app deployed to a separate server. As a low-complexity alternative that can perhaps be good enough is the following: Put perf tests into their own project, set parallelizeAssembly and parallelizeTestCollections to false, so each perf test runs alone. This way, while we'll run the test on the same machine as the app, we minimize interference and even if the absolute numbers wouldn't be indicative of the prod environment, the results would be comparable with each other.
• We could also run Google Lighthouse, also from a .NET library (but probably this will be included in Atata too). A CLI is also available.

Jira issue

[Piedone]

Related: #93.