fstests: btrfs/131: add explicit v1 space cache requirement

fstests: btrfs/131: add explicit v1 space cache requirement

The test case is utilizing v1 space cache, meanwhile v1 space cache
is already marked deprecated for a while since kernel commit
1e7bec1f7d65 ("btrfs: emit a warning about space cache v1 being
deprecated").

Furthermore quite some features are not compatible with v1 cache,
including the soon-to-be-default block-group-tree, and hardware
dependent zoned features.

Currently we reject those features for btrfs/131, but what we really
want is to only run the test case for supported features/kernels.
The current way to reject will not handle future kernels that completely
rejects v1 space cache.

Add a new helper, _require_btrfs_v1_cache() to do the check, which
checks the following criteria:

- "space_cache=v1" mount option is supported
  And to handle default v2 cache behavior, also add "clear_cache".
  If the kernel has completely dropped v1 cache support, such mount
  should fail.

- Check if FREE_SPACE_TREE feature exists after above mount
  For bs != ps cases, v2 cache is enforced to replace v1 cache, thus
  we need to double check to make sure above mount didn't result v2
  cache.

- Check if cache generation is correct
  If v1 cache is working, the cache_generation should be some valid
  value other than 0 nor (u64)-1.

And replace the existing checks on zoned and block-group-tree with the
new one.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>