Breaking changes

Removed packet_codec_param rosparam, which was deprecated in v7.0 (!57 (merged)). (This used the rosparam loader to load codec files This doesn't handle includes, and it has all sorts of weird bugs, like not being able to handle uint64 literals due to a bug in the xml parser library used by roslaunch.)

New features

Made all packet codecs accept **kwargs, so packet codec parameter dictionaries can be passed directly after parsing the codec config YAML files.
Made rosparam lookups for packet_codec_file and codec_directory recursive so these parameters can be put in a higher level namespace and reused across nodes (in the message_queue and packet_dispatch nodes).
Moved large chunks of the packet codec configuration to config_parser.py to reduce duplication.
Added src parameter that can be passed to packet codecs.
Made DecoderListEntry in packet_dispatch_node.py a normal class (it was a dataclass) so that it can accept **kwargs.
Fixes and improvements to the packet codec plugin system (it no longer modifies the Python path when loading plugins).