Adds new prometheus metrics from the configured log list and configured
CT logs to the ctpolicy constructor. `ct_operator_group_size_gauge`
returns the number of configured logs managed by each operator in the
log list. `ct_shard_expiration_seconds` returns a Unix timestamp
representation of the `end_exclusive` field for each configured log in
the `sctLogs` list. For posterity, Boulder retrieves SCTs from logs in
the `sctLogs` list.
```
ct_operator_group_size_gauge{operator="Operator A",source="finalLogs"} 2
ct_operator_group_size_gauge{operator="Operator A",source="sctLogs"} 4
ct_operator_group_size_gauge{operator="Operator B",source="sctLogs"} 2
ct_operator_group_size_gauge{operator="Operator D",source="sctLogs"} 1
ct_operator_group_size_gauge{operator="Operator F",source="finalLogs"} 1
ct_operator_group_size_gauge{operator="Operator F",source="infoLogs"} 1
ct_shard_expiration_seconds{logID="A1 Current",operator="Operator A"} 3.15576e+09
ct_shard_expiration_seconds{logID="A1 Future",operator="Operator A"} 3.47126688e+10
ct_shard_expiration_seconds{logID="A2 Current",operator="Operator A"} 3.15576e+09
ct_shard_expiration_seconds{logID="A2 Past",operator="Operator A"} 0
ct_shard_expiration_seconds{logID="B1",operator="Operator B"} 3.15576e+09
ct_shard_expiration_seconds{logID="B2",operator="Operator B"} 3.15576e+09
ct_shard_expiration_seconds{logID="D1",operator="Operator D"} 3.15576e+09
```
Fixes https://github.com/letsencrypt/boulder/issues/5705
23a0a71b2d