Merge branch 'tools-ynl-gen-add-support-for-inherited-selector-and-therefore-tc'

Jakub Kicinski says:

====================
tools: ynl-gen: add support for "inherited" selector and therefore TC

Add C codegen support for constructs needed by TC, namely passing
sub-message selector from a lower nest, and sub-messages with
fixed headers.
====================

Link: https://patch.msgid.link/20250520161916.413298-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>