tests/test-hgk.t

largefiles: always create the cache and standin directories when cloning

The standin matcher only works if the .hglf directory exists (and it won't exist
if 'clone -U' is used, unless --all-largefiles is also specified).  Since not
even 'update -r null' will get rid of the standin directory, this ensures that
the standin directory always exists if the repo has the 'largefiles'
requirement.  This requirement is only set after a largefile is committed, so
these directories will not be created for repos that have the extension enabled
but have not committed a largefile.

With the standin directory in place, 'lfconvert --to-normal' will now be able to
download the required largefiles when converting a repo that was created with
'clone -U', and whose files are not in the usercache.

The downloadlfiles command could probably be put inside the 'largefiles'
requirement conditional too, but given that the user specified --all-largefiles,
there is likely an expectation to print out the number of largefiles downloaded,
even if it is 0.

Minimal hgk check

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "hgk=" >> $HGRCPATH
  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ hg debug-cat-file commit 0
  tree a0c8bcbbb45c
  parent 000000000000
  author test 0 0
  committer test 0 0
  revision 0
  branch default
  
  adda

  $ cd ..