Merge branch 'tools-ynl-gen-split-presence-metadata'

Jakub Kicinski says:

====================
tools: ynl-gen: split presence metadata

The presence metadata indicates whether given attribute was/should be
added to the Netlink message. We have 3 types of such metadata:
 - bit presence for simple values like integers,
 - len presence for variable size attrs, like binary and strings,
 - count for arrays.

Previously this information was spread around with first two types
living in a dedicated sub-struct called _present. The counts resided
directly in the main struct with an n_ prefix.

Reshuffle these an uniformly store them in dedicated sub-structs.
The immediate motivation is that current scheme causes name collisions
for TC.
====================

Link: https://patch.msgid.link/20250505165208.248049-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>