internal data structures should serialize to disk after dispatch completes

[dustmop]

TODO from dispatch PR: https://github.com/qri-io/qri/pull/1653/files
// TODO(dustmop): If the method wrote to our internal data structures, like
// refstore, logbook, etc, serialize and commit those changes here

As dispatch is the synchronization mechanism for requests that may be running in parallel, it should also be handling changes to our internal data structures (logbook, refstore, dscache, profileStore, keyStore, etc). This allows changing data structures safely while read-only requests are running, without those requests having their data change underneath them while they are still executing, which would lead to incomprehensible bugs.