Add reindexInterval and resyncInterval to config settings

[brendan-kellam]

This PR makes it s.t., the reindex interval and resync interval are configurable via config.settings:

{
    "$schema": "./schemas/v2/index.json",
    "settings": {
        "autoDeleteStaleRepos": true,
        "reindexInterval": 3600000,
        "resyncInterval": 86400000
    },
    ...
}