Fix BLAKE3 tuneable and module loading on Linux and FreeBSD

Apply similar options to BLAKE3 as it is done for zfs_fletcher_4_impl.

The zfs module parameter on Linux changes from icp_blake3_impl to
zfs_blake3_impl.

You can check and set it on Linux via sysfs like this:

[bash]# cat /sys/module/zfs/parameters/zfs_blake3_impl
cycle [fastest] generic sse2 sse41 avx2

[bash]# echo sse2 > /sys/module/zfs/parameters/zfs_blake3_impl
[bash]# cat /sys/module/zfs/parameters/zfs_blake3_impl
cycle fastest generic [sse2] sse41 avx2

The modprobe module parameters may also be used now:

[bash]# modprobe zfs zfs_blake3_impl=sse41
[bash]# cat /sys/module/zfs/parameters/zfs_blake3_impl
cycle fastest generic sse2 [sse41] avx2

On FreeBSD the BLAKE3 implementation can be set via sysctl like this:

[bsd]# sysctl vfs.zfs.blake3_impl
vfs.zfs.blake3_impl: cycle [fastest] generic sse2 sse41 avx2
[bsd]# sysctl vfs.zfs.blake3_impl=sse2
vfs.zfs.blake3_impl: cycle [fastest] generic sse2 sse41 avx2 \
  -> cycle fastest generic [sse2] sse41 avx2

This commit changes also some Blake3 internals like these:

• blake3_impl_ops_t was renamed to blake3_ops_t
• all functions are named blake3_impl_NAME() now

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Co-authored-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #13725