debian:autopkgtest artifact view should have structured log browser

The debian:autopkgtest artifacts should have a specialized "Autopkgtest log" tab showing the results of each test and a structured view of the log with collapsible sections, similar to what has been implemented in ci.debian.net.

Here's an example: https://ci.debian.net/packages/d/debci/unstable/amd64/60134584/

Ideally all sections would be collapsed by default except the summary at the end and the sections showing a failure. The summary line for the section "test run" and/or "test results" should directly show the actual result (arguably both sections could be merged together). They could also be colored differently in case of FAILURE/SKIP/FLAKY.

PS: ci-team/debci!260 (merged) is the MR that implemented this for debci.