net/wifi-firmware-*: build framework and license hack cleanup

Cleanup the extra layer of "flavour" that came into the build framework
when flavours were introduced at a time when it was not planned.
Make linters some more happy. [1]

Remove the special license hack to install additional files.
If DISABLE_LICENSES is set we still installed files making builds fail [2].
One would hope to always install the lincese files but simply disable
any checking by the framework.
Introduce a new way using LICENSE_COMB=multi to install the default
license file, the extra WHENCE and any possible extra firmware license
files.  Technically this is an abuse of the system too but at least it
should work and not break non default options.

Based on:	D45369 by jrm [1]
Reported by:	pi [2]
Sponsored by:	The FreeBSD Foundation
Reviewed by:	jrm
Differential Revision: https://reviews.freebsd.org/D46124

net/wifi-firmware-*kmod: improve build logic, add flavors, update fw version

- update framework to no longer depend on local distfiles for firmware(9)
  but generate the Makefile hierarchy in post-extract.  Keep a
  Makefile.inc.in in files for simplicity.
- update extracting WHENCE parts using a local WHENCE.awk.in in files
  and a pattern to match the section(s).
- use the already prepared FWSUBS sections for flavors and add the
  FWDRV as "default".  Generate the CONFLICTS_INSTALL conflict and
  PKGNAMESUFFIX entries.  Adjust paths and logic for flavors.
  Depend on the flavors rather the combined ("default flavor") packages
  by default if someone installs wifi-firmware-kmod.
  The wifi-firmware-${name}-kmod packages are still built for older
  versions of fwget shipping in releases.
- add support for iwlwifi and ath12k firmware
- update firmware to linux-firmware.git tag: 20240513 for all drivers.

Sponsored by:	The FreeBSD Foundation
Reviewed by:	jrm
Differential Revision: https://reviews.freebsd.org/D44945