wireprotoserver: use our CBOR encoder
Moving away from the vendored package.
Again, our encoder normalizes keys differently from the vendored
package (for now), hence the test changes.
Differential Revision: https://phab.mercurial-scm.org/D4467
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username 2>/dev/null
foobar
#endif