add redo logger abstraction and example program to test multi-threaded trx

[jiangzhe]

Current group commit is similar to the implementation of MySQL, without multiple stages.
But it's not performant in multi-threaded environment.
The test of example program shows, when redo log disabled, the group commit encounters a large drop when there are more than 4 threads, contending the global mutex...
I'd like to try an optimization to use ringbuffer directly to aggregate logs to eliminate the lock in group commit.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 17.14286% with 29 lines in your changes missing coverage. Please review.

Project coverage is 72.59%. Comparing base (268e366) to head (c495693).

Files with missing lines	Patch %	Lines
doradb-storage/examples/multi_threaded_trx.rs	0.00%	17 Missing ⚠️
doradb-storage/src/trx/sys.rs	33.33%	12 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #147      +/-   ##
==========================================
- Coverage   72.68%   72.59%   -0.10%     
==========================================
  Files         130      130              
  Lines       18008    18025      +17     
==========================================
- Hits        13089    13085       -4     
- Misses       4919     4940      +21     

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