[RR-187] Add migration trace level

[tezc]

Adding TRACE level log for migration.

Currently, it only prints logs for locked_keys operations.
It can be extend further if required.

To enable TRACE level logs, we need to set log level of Redis and RedisRaft first:

config set loglevel debug
config set raft.loglevel debug

Then, we can enable TRACE log for migration:

config set raft.trace migration

Example log would be:

21168:M 18 Jan 2023 12:08:53.107 . <raft> <migration> Locking key: {key}10311
22230:M 18 Jan 2023 12:22:11.735 . <raft> <migration> Unlocking key: {key}1783
21236:C 18 Jan 2023 12:08:52.705 . <raft> <migration> Saving locked key to RDB: {key}0
21236:C 18 Jan 2023 12:08:52.705 . <raft> <migration> Saving locked key to RDB: {key}10005
21237:M 18 Jan 2023 12:08:53.132 . <raft> <migration> Rebuilding locked_keys dict from RDB
21237:M 18 Jan 2023 12:08:53.132 . <raft> <migration> Loading key to locked_keys from RDB: {key}0
21237:M 18 Jan 2023 12:08:53.132 . <raft> <migration> Loading key to locked_keys from RDB: {key}10005