Added ability to enable DCGM library log output

[nvvfedorov]

Users are now able to use the "--enable-dcgm-log" and "--dcgm-log-level=[NONE,FATAL,ERROR,WARN,INFO,DEBUG,VERB]" flags to enable DCGM library log output into the dcgm-exporter logs.

Important: The default value for the "--dcgm-log-level" is "NONE". To see DCGM logs, you must set at least the INFO log level.

Here is an example of the DCGM log output:

time="2024-03-01T14:24:35-06:00" level=info msg="version:3.3.3;arch:x86_64;buildtype:Release;buildid:11;builddate:2024-01-18;commit:c3aed64480553cd5ba1a32d165c7967936446631;branch:rel_dcgm_3_3;buildplatform:Linux 4.15.0-180-generic #189-Ubuntu SMP Wed May 18 14:13:57 UTC 2022 x86_64;;crc:39ff792f5514bdc5af56ce313a8fa90e [/workspaces/dcgm-rel_dcgm_3_3-postmerge/dcgmlib/src/DcgmApi.cpp:5012] [{anonymous}::StartEmbeddedV2]" dcgm_level=INFO
time="2024-03-01T14:24:35-06:00" level=info msg="Signal 12 is already handled. Nothing to do. [/workspaces/dcgm-rel_dcgm_3_3-postmerge/common/DcgmThread/DcgmThread.cpp:394] [DcgmThread::InstallSignalHandler]" dcgm_level=INFO
time="2024-03-01T14:24:35-06:00" level=info msg="Parsed driver string is 5452902, IsR450OrNewer: 1, IsR520OrNewer: 1 [/workspaces/dcgm-rel_dcgm_3_3-postmerge/dcgmlib/src/DcgmCacheManager.cpp:2592] [DcgmCacheManager::ReadAndCacheDriverVersions]" dcgm_level=INFO
time="2024-03-01T14:24:35-06:00" level=info msg="Detected 0 NVLinks for GPU 0 [/workspaces/dcgm-rel_dcgm_3_3-postmerge/dcgmlib/src/DcgmCacheManager.cpp:1263] [DcgmCacheManager::InitializeNvLinkCount]" dcgm_level=INFO
time="2024-03-01T14:24:35-06:00" level=info msg="Got 0 excluded GPUs [/workspaces/dcgm-rel_dcgm_3_3-postmerge/dcgmlib/src/DcgmCacheManager.cpp:1087] [DcgmCacheManager::ReadAndCacheGpuExclusionList]" dcgm_level=INFO

[rohit-arora-dev]

Just couple of minor suggestions based on your recent changes otherwise looking good. Thanks for addressing the review comments.

[rohit-arora-dev]

Thanks @nvvfedorov for this change and addressing the review comments.

/LGTM