Instead of separately tracking the token.
Also changes serviceMap to have a channel version of RemoveAndWait, so
that it's possible to do the removal under a lock but wait outside of
the lock. And changed where we do that in connection close, reversing
the change that happened when I added the serviceMap in 40b3b9ad1.
This adds support for syncing extended attributes on supported
filesystem on Linux, macOS, FreeBSD and NetBSD. Windows is currently
excluded because the APIs seem onerous and annoying and frankly the uses
cases seem few and far between. On Unixes this also covers ACLs as those
are stored as extended attributes.
Similar to ownership syncing this will optional & opt-in, which two
settings controlling the main behavior: one to "sync" xattrs (read &
write) and another one to "scan" xattrs (only read them so other devices
can "sync" them, but not apply any locally).
Co-authored-by: Tomasz Wilczyński <twilczynski@naver.com>
