dashboard/app: sort bugs by the impact by default

[tarasmadan]

Is your feature request related to a problem? Please describe.
Currently we sort bugs by the reported date. It prioritizes bugs in a LIFO way.
LIFO is the way syzbot maintainers tend to review them.

What regular user wants is to see them prioritized by impact.
It is especially important for the overwhelmed or the new (overwhelmed by default) customers.

Describe the solution you'd like
Sorting them by the some impact score is the way to go.
We can add 1 more column with the impact and make this ordering default.
Our intuition is good enough to give some numbers having only the title.

KASAN > GPF > KMSAN > KCSAN > BUG > WARNING > INFO or something like this.
We can discuss these details in the actual PR.

Thanks @ramosian-glider for the inspiration to do it now.

TODO:

• pkg/report: factor out type definitions #6121
• pkg/report: start using crash.KMSAN #6117
• Refactor graph.go is order to use the crash.Types. -> dashboard/app: use crash types instead, no regexps #6144
• pkg/report: split KASAN bugs #6151
• pkg/report: split kmsan #6153
• pkg/report: use crash.KASANUnknown instead of crash.KASANOther #6154
• pkg/report: split crash.KCSAN #6156
• pkg/report: split crash.KFENCE #6160
• dashboard/app: sort bugs by impact #6072
• pkg/report: introduce null ptr crash types #6170 (see comment).
• linkify the "Rank" column title to the rationale documentation page

[dvyukov]

We can add 1 more column with the impact and make this ordering default.

We don't sort by impact by default. Is it intentionally omitted, or an oversight?
Users still see the old list, and may not realize they need to click on Rank column.

[tarasmadan]

I wasn't sure this sorting will be the better option for the majority of visitors.
But I agree, it was better to make this decision loudly.