Improve error message for invalid entry name in node config

Actually there is:

raise KeyError("Wrong config entry name")

But when user see this error, it's hard to figure out which key were passed (example here: https://gitlab.syncad.com/hive/hive/-/jobs/297134).

Something like this would be much easier to work with:

raise KeyError(f'Invalid config entry name "{key_to_check}".')

Consider also provide additional context. This function is used only in following call chain:

• Node.dump_config,
• NodeConfig.load_from_file,
• NodeConfig.load_from_lines,
• NodeConfig.__check_if_key_from_file_is_valid.

Exception can be catched on Node.dump_config level and provide description such as Node dumped config with entry not known to TestTools and this description can be followed by above Invalid config entry name "some_invalid_name". It can be achieved by raise Exception() from previous_exception.