FOGL-7959 Improve error handling for plugin load failure

[MarkRiddoch]

Capture some of the reason plugins fail to load and give the user a better indication of the problem
Make the get_plugin_info utility log errors to the error log. This allows users to see missing dependecies when dynamically linking in C++ plugins

[ashish-jabble]

C based unit tests are failing

00:19:21 CMakeFiles/RunTests.dir/home/ubuntu/Fledge_PR/C/common/config_category.cpp.o: In function `ConfigCategories::ConfigCategories(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
00:19:21 /home/ubuntu/Fledge_PR/C/common/config_category.cpp:49: undefined reference to `StringAround(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, unsigned int, unsigned int, unsigned int)'
00:19:21 CMakeFiles/RunTests.dir/home/ubuntu/Fledge_PR/C/common/config_category.cpp.o: In function `ConfigCategory::ConfigCategory(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
00:19:21 /home/ubuntu/Fledge_PR/C/common/config_category.cpp:147: undefined reference to `StringAround(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, unsigned int, unsigned int, unsigned int)'
00:19:21 collect2: error: ld returned 1 exit status
00:19:21 make[2]: *** [RunTests] Error 1
00:19:21 make[1]: *** [CMakeFiles/RunTests.dir/all] Error 2
00:19:21 make: *** [all] Error 2
00:19:21 Tests for ./services/storage/postgres failed

[ashish-jabble]

No harm to keep specific exception type catch block here. But as we already have multi line stack trace support available at python side; So these type of errors will catch in general exception block and definitely it points to exact problem cause error.

Use multi line stack trace logger style.

_logger.error(err, "Failed to parse JSON data returned from the plugin information of {}.".format(name))

[MarkRiddoch]

The concept here is to give the user a very clear error message they can pick up on rather than expect them to look at something more general and work out what went wrong.

[ashish-jabble]

Sure. Previously, if we have some invalid JSON for a plugin it raises below
ERROR: logger: fledge.services.core.api.utils: json.decoder.JSONDecodeError: Expecting ',' delimiter: line 1 column 2870 (char 2869)

And with the given change
ERROR: logger: fledge.services.core.api.utils: Failed to parse JSON data returned from the plugin information of PLUGIN_NAME, Expecting ',' delimiter line 1 column 2870

So the trailing message still seems to be more developer related logger.

[AmandeepArora]

May be retain fprintf to stderr also (in addition to syslog) so that errors can be seen on console also.