This uses the following accessor methods in more places in more places:
`is_group()`, `is_group_input()`, `is_group_output()`, `is_muted()`,
`is_frame()` and `is_reroute()`.
This results in simpler code and reduces the use of `bNode.type_legacy`.
Pull Request: https://projects.blender.org/blender/blender/pulls/132899
987003d456