Add classes for Task and SharedTask in threadpool #7540

Job	Run time
ci1 / ubuntu-22.04 - AZURE	1m 15s
ci2 / ubuntu-20.04 - GCS	1m 11s
ci3 / ubuntu-22.04 - SERIALIZATION	1m 30s
ci_manylinux / ubuntu-20.04 - MANYLINUX	30s
ci4 / macos-latest - S3	21m 14s
ci5 / macos-latest - GCS	16m 45s
ci6 / ubuntu-22.04 - Experimental	1m 34s
ci7 / ubuntu-22.04 - S3	1m 31s
ci8 / ubuntu-20.04 - ASAN	44m 42s
ci9 / macos-latest - AZURE	11m 12s
ci_docker / build-dockerfile	14m 25s
backward_compatibility / Build tiledb_unit (ubuntu-20.04)	5m 6s
ci_mingw_r / build (ucrt64, ucrt-x86_64)	21m 6s
standalone / Build - macos-latest	36m 6s
ci_msvc / windows-2019 - azure	34m 32s
standalone / Build - ubuntu-latest	22m 33s
ci_msvc / windows-2019 - s3	36m 15s
standalone / Build - windows-latest	1h 3m 19s
ci_msvc / windows-2019 - gcs	38m 21s
ci_msvc / windows-2019 - serialization	29m 57s
ci_msvc / windows-2022 - azure	30m 58s
ci_msvc / windows-2022 - s3	34m 17s
ci_msvc / windows-2022 - gcs	30m 14s
ci_msvc / windows-2022 - serialization	28m 1s
backward_compatibility / ${{ matrix.tiledb_version }}	0s
full_ci_passed	0s
	8h 46m 34s

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