Snap sync downloader logging

[macfarla]

• use non-static logger field so that SnapSyncDownloader will own the logging lines
  • Note this is a departure from the standard Logger field used elsewhere in the codebase. However it is flagged by the annotation so it's obvious. Couldn't think of a nicer way to do this but open to suggestions
• rename SnapsyncMetricsManager to SnapSync... for consistency
• rename FastImportBlockStep to ImportBlockStep
• rename SyncTargetManager to AbstractSyncTargetManager and FastSyncTargetManager to SyncTargetManager
• rename FastSyncException to SyncException

fixes #6386

[github-actions]

• I thought about documentation and added the doc-change-required label to this PR if updates are required.
• I thought about the changelog and included a changelog update if required.
• If my PR includes database changes (e.g. KeyValueSegmentIdentifier) I have thought about compatibility and performed forwards and backwards compatibility tests

[macfarla]

before

2024-01-15 12:54:49.957 | {"@timestamp":"2024-01-15T02:54:49,828","level":"INFO","thread":"EthScheduler-Services-42 (importBlock)","class":"FastImportBlocksStep","message":"Block import progress: 2215600 of 19009156 (11%)","throwable":""}
-- | --

...

2024-01-15 11:39:06.716 | {"@timestamp":"2024-01-15T01:39:06,590","level":"INFO","thread":"EthScheduler-Timer-0","class":"FastSyncTargetManager","message":"Unable to find sync target. Currently checking 4 peers for usefulness.","throwable":""}
  |   | 2024-01-15 11:35:40.800 | {"@timestamp":"2024-01-15T01:35:23,083","level":"INFO","thread":"beaconchain-async-3","class":"HistoricalBlockSyncService","message":"Begin historical sync of blocks from slot 8204768 to slot 7147999","throwable":""} |  
  |   | 2024-01-15 11:35:40.799 | {"@timestamp":"2024-01-15T01:35:22,635","level":"INFO","thread":"beaconchain-async-1","class":"DefaultSyncServiceFactory","message":"Using multipeer sync","throwable":""} |  
  |   | 2024-01-15 11:35:40.799 | {"@timestamp":"2024-01-15T01:35:23,597","level":"INFO","thread":"vert.x-worker-thread-0","class":"BackwardSyncContext","message":"Starting a new backward sync session","throwable":""} |  
  |   | 2024-01-15 11:35:40.799 | {"@timestamp":"2024-01-15T01:35:03,308","level":"INFO","thread":"main","class":"FastSyncDownloader","message":"Starting sync","throwable":""} |  
  |   | 2024-01-15 11:35:40.799 | {"@timestamp":"2024-01-15T01:35:03,307","level":"INFO","thread":"main","class":"DefaultSynchronizer","message":"Starting synchronizer.","throwable":""} |  
  |   | 2024-01-15 11:35:40.798 | {"@timestamp":"2024-01-15T01:35:02,424","level":"INFO","thread":"main","class":"TransitionBesuControllerBuilder","message":"TTD present, creating DefaultSynchronizer that stops propagating after finalization","throwable":""}

[macfarla]

after (not necessarily in order)

2024-01-15 13:14:17.529 | {"@timestamp":"2024-01-15T03:14:17,454","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapSyncMetricsManager","message":"Worldstate download progress: 0.23%, Peer count: 3","throwable":""} |  
-- | -- | --
  |   | 2024-01-15 13:12:27.239 | {"@timestamp":"2024-01-15T03:12:27,088","level":"INFO","thread":"EthScheduler-Services-3 (batchPersistAccountData)","class":"SnapSyncMetricsManager","message":"Worldstate download progress: 0.16%, Peer count: 2","throwable":""} |  
  |   | 2024-01-15 13:11:26.999 | {"@timestamp":"2024-01-15T03:11:26,974","level":"INFO","thread":"nioEventLoopGroup-3-4","class":"SnapWorldStateDownloader","message":"Downloading world state from peers for pivot block 19009411 (0x8d227244c7a58309255b9cc70170657e3f9dba4fd9c422fe79e0446de4867f7c). State root 0xa2bcf08d998fc5d6d1a79645d822b451e0342b9a911ec6b3cccbd2eff5a693e7 pending requests 0","throwable":""} |  
  |   | 2024-01-15 13:11:23.986 | {"@timestamp":"2024-01-15T03:10:55,649","level":"INFO","thread":"main","class":"SnapSyncDownloader","message":"Starting sync","throwable":""}

...

2024-01-15 12:23:16.145 | {"@timestamp":"2024-01-15T02:22:59,420","level":"INFO","thread":"vert.x-worker-thread-0","class":"BackwardSyncContext","message":"Starting a new backward sync session","throwable":""} |  
-- | -- | --
  |   | 2024-01-15 12:23:16.144 | {"@timestamp":"2024-01-15T02:22:42,378","level":"INFO","thread":"main","class":"DefaultSynchronizer","message":"Starting synchronizer.","throwable":""} |  

[Gabriel-Trintinalia]

LGTM