clickhouse-backup watch mode

[Slach]

• implements CLI watch command and API /backup/watch for run periodic backup cycle (simplify ACM workflow)

  • allow params 'watch-interval', 'full-interval', 'wach-backup-name-template' via CLI and config
  • allow same params as for create_remote, like tables, (not allow resumable, retry policy enough)
  • internal commands in API /backup/watch shall run in-progress, similar when allow_parallel=true
  • multiple watch API command allow only when alllow_parallel=true and should contains different params
  • implements clickhouse-backup server --watch when WatchHandler run after start
  • check backups_keep_remote enough for 1 full backup cycle and it's not 0
  • shall stop for /restart and kill API command
  • run create_remote full + delete local full, even when upload failed, save previous backup type empty, next try will also full
  • each watch interval, run create_remote increment --diff-from=prev-name + delete local increment, even when upload failed, save previous backup type, next try will also incremental, until full-interval

• agree with inefficient for use case when one big part constantly merging with many small parts