…vent messages, reverse LogPrintLevel order

c4e7717 refactor: Change LogPrintLevel order to category, severity (laanwj)
ce92071 leveldb: Log messages from leveldb with category and debug level (laanwj)
18ec120 http: Use severity-based logging for messages from libevent (laanwj)
bd971bf logging: Unconditionally log levels >= WARN (laanwj)

Pull request description:

  Log messages from leveldb and libevent libraries in the severity+level based log format introduced in bitcoin#24464.

  Example of messages before:
  ```
  2022-05-24T18:11:57Z [libevent] libevent: event_add: event: 0x55da963fcc10 (fd 10), EV_READ    call 0x7f1c7a254620
  2022-05-24T18:11:57Z [libevent] libevent: Epoll ADD(1) on fd 10 okay. Old events were 0; read change was 1 (add); write change was 0 (none); close change was 0 (none)
  2022-05-24T18:12:08Z leveldb: Generated table #609127@1: 6445 keys, 312916 bytes
  2022-05-24T18:12:08Z leveldb: Generated table #609128@1: 5607 keys, 268548 bytes
  2022-05-24T18:12:08Z leveldb: Generated table #609129@1: 189 keys, 9384 bytes
  2022-05-24T18:12:08Z leveldb: Generated table #609130@1: 293 keys, 13818 bytes
  ```

  Example of messages after:
  ```
  2022-05-24T17:59:52Z [libevent:debug] event_add: event: 0x5652f44dac10 (fd 10), EV_READ    call 0x7f210f2e6620
  2022-05-24T17:59:52Z [libevent:debug] Epoll ADD(1) on fd 10 okay. Old events were 0; read change was 1 (add); write change was 0 (none); close change was 0 (none)
  2022-05-24T17:59:53Z [leveldb:debug] Recovering log dashpay#1072
  2022-05-24T17:59:53Z [leveldb:debug] Level-0 table dashpay#1082: started
  2022-05-24T17:59:53Z [leveldb:debug] Level-0 table dashpay#1082: 193 bytes OK
  2022-05-24T17:59:53Z [leveldb:debug] Delete type=3 dashpay#1070
  2022-05-24T17:59:53Z [leveldb:debug] Delete type=0 dashpay#1072
  ```

  The first commit changes it so that messages with level Warning and Error are always logged independent of the `-debug` setting. I think this is useful to make sure warnings and errors, which tend to be important, are not lost. In the future this should be made more configurable.

  Last commit changes LogPrintLevel argument order to category, severity: This is more consistent with the other functions, as well as with the logging output itself. If we want to make this change, we should do it before it's all over the place.

ACKs for top commit:
  jonatack:
    Tested ACK c4e7717

Tree-SHA512: ea48a1517f8c1b23760e59933bbd64ebf09c32eb947e31b8c2696b4630ac1f4303b126720183e2de052bcede3a17e475bbf3fbb6378a12b0fa8f3582d610930d