Enhancement: Adjust binary file location (#535)

[yadunand-kamath]

Previously, all unittest files and binary executable files (such as observer/obclient) were put together in build_*/bin directory.
After the enhancement, the binary executable files and the unittest files have been separated into the following directories respectively:

• build_*/bin
• build_*/unittest

Issue Number: close #535

After enhancement

> cd build_debug
> ls bin/
clog_dump  cpplings  obclient  oblsm_bench  oblsm_cli  observer
> ls unittesttest/
CMakeFiles                 bplus_tree_log_entry_test  codec_test                integer_generator_test  mem_pool_test        ob_lsm_test       pax_storage_test     thread_pool_executor_test
CTestTestfile.cmake        bplus_tree_log_test        common                    log_buffer_test         mvcc_trx_log_test    ob_skiplist_test  persist_test
Makefile                   bplus_tree_test            composite_tuple_test      log_entry_test          ob_arena_test        ob_table_test     pidfile_test
aggregate_hash_table_test  buffer_pool_log_test       disk_buffer_pool_test     log_file_test           ob_block_test        ob_util_test      record_manager_test
arithmetic_operator_test   catalog_test               disk_log_handler_test     log_test                ob_bloomfilter_test  oblsm             ring_buffer_test
bitmap_test                chunk_test                 double_write_buffer_test  lower_bound_test        ob_compaction_test   observer          serializer_test
bp_manager_test            cmake_install.cmake        expression_test           md5_test                ob_lru_cache_test    parser_test       simple_queue_test

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[nautaa]

can you resolve ci fail? @yadunand-kamath

[nautaa]

putting binary file in ${PROJECT_BINARY_DIR}/bin and putting ut file in ${PROJECT_BINARY_DIR}/unittest is better?

[yadunand-kamath]

ok I'll do that

[nautaa]

thanks for your contribution, and can you resolve the ci fail? maybe you need to change some file paths in github workflow. @yadunand-kamath

[nautaa]

@yadunand-kamath please take a look again, thank you!