Trees in audit details

[matejchalk]

User story

Reporting uncovered lines/branches/functions as individual issues in the coverage plugin isn't very consumer-friendly (too verbose) and has a big impact on data storage size. A more compact and understandable output format would be welcome. A table would be an option for coverage, although an expandable file tree would be even more convenient. This tree format would be applicable to some Lighthouse audit outputs as well.

Design - PoC

See Markdown formatting options here.

Implementation plan

• [x] #994
• [x] code-pushup/portal#596
• [x] #996
• [x] #997
• [ ] code-pushup/portal#597
• [x] #999
• [x] #1000
• [x] #1001