Migrate blacklist functionality to file

[ezeoleaf]

Is your feature request related to a problem? Please describe.
Yes, Redis is not keeping the blacklist keys indefinitely, so ideally we will read from a blacklist file every 5 minutes and load the blacklisted repositories in memory to be used as our cache.

Describe the solution you'd like
See above

Describe alternatives you've considered
Perhaps a db but that could be messier. Or instead of a go routine, using an endpoint to accept new repository to blacklist and then update the blacklisted list.

Additional context
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