Add end times to static masking

[ljgray]

Add specification of end times for static rfi masking so we can unmask a band if the rfi source shuts off.

I haven't actually updated the list of bad frequencies with known end times yet.

[jrs65]

Sweet, I was just thinking of doing this.

You might as well add the end times for those bands in there while you're on. Let me just go and dig into those spectrum plots to figure them out and I'll post them here.

[jrs65]

End dates:

• TV channel 27 (548–554 MHz): 2022-08-24
• TV channel 32 (578–584 MHz): 2022-08-25

They're both definitely gone by midnight UTC on those dates,

[ljgray]

@jrs65 I've added those bands, which end on CSD 3212 and 3213 (inclusive) respectively (i.e. the first good day for the bands are 3213 and 3214). Can you confirm that that's correct, or would CSD 3212 and 3213 be the first days without the bands?