dashboard/app: integrate with regzbot

[dvyukov]

regzbot info:
https://docs.kernel.org/admin-guide/reporting-regressions.html
https://linux-regtracking.leemhuis.info/regzbot/mainline/
https://lpc.events/event/16/contributions/1222/attachments/1105/2123/Leemhuis-regtracking.pdf

When we report a cause bisection, we could cc regressions@lists.linux.dev and add #regzbot introduced tag to the report. Presumably it will be enough for the regzbot to start tracking it.

[dvyukov]

cc @knurd fyi