Adds delegation checker

[nils-wisiol]

• periodically checks delegation status of all domains
• implements limits on insecure domains per user
• sets default limit to unlimited
• updates the UI to show the detected delegation status
• updates the UI to allow triggering of the delegation check for a given domain

delegation checker run times on my laptop on a 1000 domains sample (5 repeats):

Threads	Mean (s)	Stdev (s)	Speedup vs 1x	100k extrapolation
1	178.07	21.53	1.00x	~296.8 min (4.95 h)
10	39.12	13.79	4.55x	~65.2 min (1.09 h)
20	33.20	8.06	5.36x	~55.3 min (0.92 h)
50	23.89	6.38	7.46x	~39.8 min (0.66 h)
100	26.10	6.14	6.82x	~43.5 min (0.73 h)
200	27.16	6.15	6.55x	~45.3 min (0.75 h)

The delegation checker is not comparing keys against nslord to avoid making many requests to nslord.