syzbot: exporting downloadable archives of the open/fixed bugs

[a-nogikh]

We currently share bug lists and per-bug information via a JSON API which requires multiple queries (linear to the number of bugs) and which is subject to request throttling.

There have been a number of requests from external and internal parties that could be resolved by sharing a downloadable .tar.gz archive with all that information.

So far, it looks like the archive should be of the following form:

1. Multiple folders at root, one folder per bug.
2. For each bug, a JSON description with the basic information (title, status, fix/cause bisections).
3. For each bug, a crashes folder with N (up to 10?) most relevant crashes. For each crash:
   3.a) General info (crash title, date, arch, kernel and syzkaller revisions)
   3.b) Crash report
   3.c) C and Syz reproducers (if present).

There are two ways we could implement it:

1. Construct and upload the archive directly from GAE.
2. Invoke a standalone tool (like tools/syz-reprolist) that will make all those API queries to the Web dashboard (without throttling) and construct the archive.

Cc @tarasmadan

[tarasmadan]

#5468 to store bugs+crashes